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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>AQAMS and AQAMS2: Multi Agent Systems for Biomedical Question Answering</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Johanna Angulo</string-name>
          <email>johanna.angulo@gmail.com</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Víctor Yeste</string-name>
          <email>victor.yeste@universidadeuropea.es</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>School of Science, Engineering and Design, Universidad Europea de Valencia</institution>
          ,
          <addr-line>Paseo de la Alameda, 7, 46010 Valencia</addr-line>
          ,
          <country country="ES">Spain</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2025</year>
      </pub-date>
      <abstract>
        <p>This paper presents AQAMS and AQAMS2, two multi-agent biomedical question answering systems developed for the BioASQ 13B challenge. Both systems employ a two-agent architecture comprising a Researcher Agent for evidence gathering and a Writer Agent for answer synthesis. AQAMS targets open-domain retrieval (Phases A/A+) using hybrid vector search and PubMed API integration, while AQAMS2 focuses on snippet-based analysis (Phase B) incorporating biomedical NER and UMLS concept mapping. AQAMS achieved 87.1% average yes/no accuracy in Phase A+, with notable adaptation capability demonstrated by 173% relative improvement in factoid questions between batches. However, performance was constrained by incomplete vector database indexing (15% of PubMed corpus). AQAMS2 demonstrated substantially improved performance in Phase B, achieving up to 95.45% yes/no accuracy, 63.1% list F-measure, and 18.88% ROUGE-2 F1 for ideal answers, representing peak improvements of 51-183% across metrics compared to Phase A+. In comprehensive evaluation across all batches, AQAMS2 demonstrated competitive performance while indicating areas for improvement. The comparative analysis reveals that multi-agent coordination performs more efectively with high-quality, focused context compared to broad retrieval scenarios. The architecture demonstrates measurable benefits for systematic integration of heterogeneous tools and adaptive processing capabilities. While the results validate the viability of the multi-agent approach for biomedical question answering, they indicate that further development is needed to achieve performance comparable to leading systems in this challenging domain.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;Biomedical Question Answering</kwd>
        <kwd>GenAI</kwd>
        <kwd>AI Agents</kwd>
        <kwd>Large Language Models</kwd>
        <kwd>Prompt Engineering</kwd>
        <kwd>RAG</kwd>
        <kwd>BioASQ 13B</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>
        Recent advances in Natural Language Processing (NLP) and Information Retrieval (IR) have significantly
enhanced the capability to answer biomedical questions at scale [
        <xref ref-type="bibr" rid="ref1 ref2">1, 2</xref>
        ]. The BioASQ challenge series
provides a standardized benchmark for evaluating such systems on real-world biomedical queries,
fostering the development of advanced approaches that serve researchers and clinicians. Task 13B of
BioASQ (2025) continued this initiative by requiring participants to build systems capable of retrieving
relevant information and generating accurate answers for questions posed by biomedical experts [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ].
This task presents particular challenges due to the volume and complexity of biomedical literature,
which contains specialized terminology and undergoes rapid evolution [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ]. This paper describes two
complementary systems—AQAMS and AQAMS2—developed for BioASQ 13B Task B, which leverage the
synergy between information retrieval and large language models. Both systems adopt a multi-agent
pipeline architecture where a Researcher Agent handles information gathering or analysis, followed by
a Writer Agent that produces final answers. AQAMS was designed for the open-retrieval scenario of
Phase A and A+ (where systems retrieve answers from the entire biomedical literature), while AQAMS2
was tailored for the closed-snippet scenario of Phase B (where relevant text snippets are provided by
the organizers). By integrating vector-based semantic search, traditional API-based retrieval, prompt
engineering techniques [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ], and biomedical NER with UMLS concept mapping, our systems aim to
deliver both precise "exact" answers and comprehensive "ideal" answers. We evaluate the performance
of AQAMS and AQAMS2 on the oficial BioASQ 13B test batches and compare their efectiveness across
diferent question types (yes/no, factoid, list, summary). We also analyze the impact of our design
choices in the context of recent work in biomedical question answering, including hybrid retrieval
pipelines and few-shot prompt templates, and discuss potential improvements. The remainder of this
paper is organized as follows: Section 2 describes the BioASQ 13B task setup; Section 3 provides an
overview of the techniques used; Section 4 details the methodology of our AQAMS and AQAMS2
systems; Section 5 presents the experimental results; Section 6 ofers analysis and discussion; and
Section 7 outlines future research directions.
      </p>
    </sec>
    <sec id="sec-2">
      <title>2. Overview of the Task 13B</title>
      <p>
        BioASQ is a series of international challenges that promotes advances in large-scale biomedical semantic
indexing and question answering [
        <xref ref-type="bibr" rid="ref6 ref7 ref8">6, 7, 8</xref>
        ]. The BioASQ challenge serves as a long-running benchmark
for biomedical question answering, with recent editions (2023–2024) demonstrating notable progress in
the field [
        <xref ref-type="bibr" rid="ref8 ref9">9, 8</xref>
        ]. Competing systems address distinct challenges across multiple phases. Phase A focuses
on information retrieval from PubMed articles to identify relevant snippets for specific questions.
In Phase A+, participants must address multiple question types (yes/no, factoid, list, summary) by
retrieving relevant literature from PubMed and providing both exact answers and paragraph-length
ideal answers. Phase B requires participants to provide exact and ideal answers using provided text
snippets. Overall performance has improved consistently year over year, and in BioASQ 2024, "most of
the participating systems achieved competitive performance, suggesting the continuous advancement of
the state-of-the-art in the field" [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]. Large language models have made a significant impact on biomedical
question answering performance. One study demonstrated that GPT-4 and GPT-3.5 (ChatGPT) in a
zero-shot setting, when provided with relevant snippets, could nearly match the performance of the best
BioASQ 11b systems on factoid and list questions [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ]. This finding underscores the rapid advancement
achieved by general domain models even without domain-specific fine-tuning. In 2024 (BioASQ 12b), this
trend continued with many teams integrating generative large language models with retrieval systems.
Nentidis et al. reported strong results from systems that combine information retrieval with
GPTbased answer generation [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ]. The BioASQ challenge results from 2023–2025 highlight that ensemble
approaches combining retrieval modules with large pre-trained models now dominate biomedical
question answering, significantly outperforming earlier methodologies. The availability of the manually
curated BioASQ dataset, containing thousands of question-answer pairs and gold standard snippets,
continues to enable these advances [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ].
      </p>
    </sec>
    <sec id="sec-3">
      <title>3. Overview of Used Techniques</title>
      <p>This section summarizes recent advances in the field and situates the techniques employed in our
participating systems within the context of the current state of the art.</p>
      <sec id="sec-3-1">
        <title>3.1. Multiagent systems</title>
        <p>
          The developed system is based on multiagent architecture principles, defined as a computational
paradigm where multiple autonomous entities (agents) collaborate to solve complex problems that
exceed the capabilities of monolithic systems [
          <xref ref-type="bibr" rid="ref12">12</xref>
          ]. In the biomedical context, multiagent systems have
demonstrated particular efectiveness in handling the inherent complexity of the medical domain, where
diferent aspects of information processing require specialized expertise [
          <xref ref-type="bibr" rid="ref13">13</xref>
          ].
        </p>
        <p>
          According to Ferber’s taxonomy [
          <xref ref-type="bibr" rid="ref14">14</xref>
          ], the implemented Q&amp;A system corresponds to a cooperative
multiagent architecture where agents share common objectives and collaborate to maximize the global
utility of the system. This classification aligns with the coherence and precision requirements necessary
in biomedical applications [
          <xref ref-type="bibr" rid="ref15">15</xref>
          ].
        </p>
        <p>
          Following Russell and Norvig’s taxonomy [
          <xref ref-type="bibr" rid="ref16">16</xref>
          ], the implemented agents can be classified as goal-based
agents that maintain internal representations of the problem state and use domain-specific knowledge
to make decisions.
        </p>
      </sec>
      <sec id="sec-3-2">
        <title>3.2. Retrieval-Augmented Generation</title>
        <p>
          Retrieval-Augmented Generation (RAG) has emerged as a pivotal approach for biomedical question
answering in recent years. RAG systems integrate a document retrieval component with a text generation
model, enabling large language models to ground their answers in external knowledge [
          <xref ref-type="bibr" rid="ref17">17</xref>
          ]. This is
particularly important in biomedicine, where up-to-date factual accuracy is required beyond an LLM’s
static training data. Multiple studies from 2023–2024 demonstrate the efectiveness of RAG in this
domain. For example, Merker et al. built a RAG-based pipeline that first retrieves PubMed abstracts
using BM25 and neural re-ranking, then feeds top snippets into GPT-3.5 or GPT-4 to generate answers
[
          <xref ref-type="bibr" rid="ref18">18</xref>
          ]. They observed that providing relevant snippets significantly improves answer accuracy, and in
their experiments, answers based on snippet-context outperformed those generated from full abstracts.
        </p>
        <p>
          Similarly, Jeong et al. introduced Self-BioRAG, a framework that augments a transformer model with
biomedical knowledge via retrieval and even a self-reflection step [ 19]. Self-BioRAG selectively pulls in
domain-specific content from curated corpora and knowledge bases and was shown to boost accuracy
by approximately 7–8% over baseline LLMs on medical QA benchmarks. These improvements echo the
general findings in open-domain QA that RAG can reduce hallucinations and inject up-to-date facts
[
          <xref ref-type="bibr" rid="ref17">17</xref>
          ]. Indeed, integrating retrieval is seen as essential in biomedicine: Zhang et al. emphasize that RAG
is "a pivotal innovation that improves the accuracy and relevance of LLM responses by integrating
LLMs with a search engine and external sources of knowledge" [
          <xref ref-type="bibr" rid="ref17">17</xref>
          ]. In practice, many state-of-the-art
biomedical QA systems now use RAG or related hybrid strategies. Traditional pipelines had separate
information retrieval and answer stages [20], but modern RAG blurs this boundary, often iteratively
retrieving and generating.
        </p>
      </sec>
      <sec id="sec-3-3">
        <title>3.3. Use of PubMed E-Utilities API in Biomedical Question Answering</title>
        <p>
          Given that PubMed/MEDLINE is the primary source of biomedical literature, many QA systems rely
on NCBI’s E-Utilities API to fetch relevant articles and snippets. The PubMed E-Utilities (RESTful
web services) enable querying the vast biomedical literature programmatically, which is crucial for
up-to-date QA. In the BioASQ challenges, for instance, participants are explicitly tasked with retrieving
answers from designated resources including PubMed/MEDLINE articles [21]. Systems therefore use
the E-Utilities (such as the esearch and efetch endpoints) to automate literature search and retrieval
of article metadata, abstracts, and even full-text snippets when available. Merker et al. describe using
the PubMed search API to retrieve up to 200 abstracts per query as an initial document set, before
applying local re-rankers [
          <xref ref-type="bibr" rid="ref18">18</xref>
          ]. This highlights that even with advanced neural methods, the pipeline
often begins with PubMed API calls to ensure comprehensive coverage of relevant papers. The NCBI
E-Utilities have thus become a standard tool: many systems incorporate modules or use libraries to
run keyword queries, possibly with MeSH term filtering. For example, the BioASQ dataset paper notes
that curators formulated multiple PubMed queries with field tags and MeSH filters for each question,
retrieving documents and snippets that systems can use [
          <xref ref-type="bibr" rid="ref11">11</xref>
          ]. The advantage of using the API is that it
provides access to the entire up-to-date MEDLINE corpus (33+ million citations) in real time [22, 23].
        </p>
      </sec>
      <sec id="sec-3-4">
        <title>3.4. Prompting Strategies and Few-Shot Prompting in Biomedical QA</title>
        <p>With the advent of large language models, prompting strategies have become critical for biomedical
QA performance. In particular, few-shot prompting – providing a handful of example Q&amp;A pairs or
instructions in the prompt – can substantially improve an LLM’s ability to specialize to biomedical
questions without fine-tuning. Research in 2023–2024 demonstrates that carefully engineered prompts
can bridge the gap between general-purpose LLMs (like GPT-3.5/GPT-4) and domain-specific needs
[24, 25].</p>
        <p>
          Few-shot prompting is especially useful in scenarios with limited training data. Ateia and Kruschwitz
explored the few-shot performance of open-source versus commercial LLMs in biomedical tasks [21].
They observed that the performance gap between GPT-4 and smaller open models can be largely closed
by providing around 10 exemplars (few-shot) – Mixtral (an 8×7B ensemble) became competitive with
GPT-4 in a 10-shot setting [21]. This finding underlines that domain-specific examples help models
follow instructions and leverage biomedical terminology more efectively. Another important strategy is
chain-of-thought prompting, where the model is guided to reason step-by-step. Merker et al. employed a
few-shot chain-of-thought prompt to extract answer-relevant snippets from abstracts [
          <xref ref-type="bibr" rid="ref18">18</xref>
          ]. By showing
the model examples of reasoning through a passage to find key information, they improved snippet
extraction performance.
        </p>
        <p>
          Prompting can also specify format and context: e.g., instructing the model to answer with a certain
style or to cite sources. In general, prompt design has become an art in biomedical QA, often involving
trial-and-error to see which instructions yield the most factual and concise answers. Empirical results
in 2023 indicate that even zero-shot, well-crafted prompts allow GPT-3.5/4 to rival specialized systems
on many tasks [
          <xref ref-type="bibr" rid="ref10">10</xref>
          ]. However, adding a few examples (few-shot) tends to further boost reliability
and reduce errors, especially for complex multi-step questions or when dealing with rare biomedical
terms. In summary, efective prompting – including few-shot exemplars, step-by-step cues, and explicit
instructions – is now recognized as a key factor in getting the best out of large generative models for
biomedical question answering [26, 21]. It allows QA systems to leverage general LLMs while injecting
domain knowledge and context through the prompt, often obviating the need for extensive model
ifne-tuning.
        </p>
      </sec>
      <sec id="sec-3-5">
        <title>3.5. Role of Named Entity Recognition (NER) in Biomedical Semantic QA</title>
        <p>
          Named Entity Recognition (NER) plays a foundational role in biomedical QA systems. Biomedical
questions and texts are dense with technical entities (drug names, genes, diseases, etc.), and identifying
these entities is crucial for understanding queries and retrieving precise answers [27]. Many pipelines
therefore include a BioNER step to tag key terms in the question and candidate passages. This has
several benefits: (1) it helps map words to standardized concepts (e.g., recognizing that "heart attack"
corresponds to myocardial infarction), (2) it guides the retrieval module by focusing on important
keywords, and (3) it can assist in answer extraction by ensuring the system outputs a properly identified
entity. Early BioASQ challenges recognized this – the benchmark datasets even provide "concepts"
(from UMLS, MeSH, etc.) associated with each question [
          <xref ref-type="bibr" rid="ref11">11</xref>
          ].
        </p>
        <p>These concepts essentially come from NER and linking performed by the curators, and they can
be used by QA systems for query expansion or checking answer correctness. Traditional approaches
to biomedical QA often featured an NER component [28]. By tagging entities in both questions and
documents, they could better match relevant information. NER is also critical in identifying the type
of answer expected. A question like "What enzyme digests fibrin?" implies the answer should be an
enzyme name – if the system’s NER can detect that, it can constrain the answer extraction to enzyme
entities [29].</p>
        <p>
          Modern transformer-based QA models implicitly learn some entity recognition, but integrating
explicit NER has still proven useful in many cases. Jin et al. in their survey highlight that handling
of synonyms and variant entity names is a big challenge in biomedical QA – which is essentially an
NER+normalization problem [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ].
        </p>
      </sec>
      <sec id="sec-3-6">
        <title>3.6. UMLS APIs and Mapping NER to UMLS Concepts</title>
        <p>The Unified Medical Language System (UMLS) is a comprehensive repository of biomedical vocabularies
and concepts, and it has been widely used to enhance QA systems. By mapping recognized entities
(via NER) to UMLS concepts, systems can normalize diferent terms to the same underlying idea and
even retrieve additional information (synonyms, definitions, related concepts) through UMLS services.
Several approaches from 2023–2025 explicitly integrate UMLS knowledge. One line of work is to use
UMLS for query expansion or synonym resolution [30]. Once entities are linked, the UMLS API (via the
NIH UMLS Terminology Services) can be used to fetch concept details: e.g., hierarchical relations, or all
synonyms in various terminologies. Incorporating this knowledge can improve recall – a QA system
might automatically expand a query with UMLS synonyms or check an answer candidate against UMLS
definitions. Recent research has also looked at injecting UMLS knowledge into language models. Park et
al. introduced a method of infusing UMLS knowledge into a transformer via adapter-based fine-tuning
[31]. By semantically partitioning the UMLS knowledge graph and training adapters, they imbued the
model with domain knowledge that improved performance on biomedical QA datasets [31].</p>
      </sec>
      <sec id="sec-3-7">
        <title>3.7. Importance of Evidence-Grounded Responses in Biomedical QA</title>
        <p>Biomedical Question Answering aims to extract an answer to the given question from a biomedical
context [32]. However, despite tremendous growth, BQA still needs to mature and faces many challenges,
such as corpora scaling, annotation, lexical answer type prediction, and complex terminology [33].
In the biomedical domain, it is critical that QA systems provide evidence-grounded responses – that
is, answers supported by authoritative sources (e.g., peer-reviewed articles). Unlike casual Q&amp;A, an
incorrect answer in healthcare could have serious consequences. Hence, recent biomedical QA research
places great emphasis on grounding and justification [34].</p>
        <p>This need for evidence-grounded responses in the biomedical field inspired us to extend our system
beyond the BioASQ 13B Challenge and, on top of exact and ideal answers, provide a "supported answer"
with references to snippets used to build the answer. We also implemented this in the user interface to
provide a user-friendly visualization of the system responses, helping to trust the AI system or realize
when the answer does not have the expected level of evidence support.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. Methodology</title>
      <p>The objective of our research is to develop a multi-agent, hybrid question answering system where
modular resources and knowledge bases interact synergistically.</p>
      <p>For that end, we have implemented a two-agent architecture for both tasks, with variations customized
to the retrieval scenario of Phase A/A+ and the snippet-based scenario of Phase B. Figure 1 outlines the
general architecture of our systems (AQAMS for Phase A/A+ and AQAMS2 for Phase B).</p>
      <p>The Researcher Agent is responsible for interpreting the question and gathering relevant evidence,
which includes querying databases or APIs in AQAMS, and performing named entity recognition (NER)
and UMLS concept mapping in AQAMS2. The Writer Agent is a large language model (GPT-4) prompted
to generate the final answers (exact and ideal, with an additional supported explanation in Phase B). We
selected an OpenAI GPT model for the Writer Agent due to its strong few-shot learning capabilities and
lfuent language generation [ 35]. To ensure domain specificity and factual accuracy, the Writer Agent is
always provided with contextual information—either retrieved snippets or extracted entities—through
a structured prompt. Below, we describe each system in detail.</p>
      <sec id="sec-4-1">
        <title>4.1. AQAMS: Phase A/A+ System</title>
        <p>AQAMS (Automated Question Answering with Multi-agent System) was developed for the open-domain
scenario of BioASQ 13B Phase A and A+. The system implements a two-stage pipeline for biomedical
question answering. In the first stage (Phase A, document/snippet retrieval), AQAMS’s Researcher
Agent performs a hybrid retrieval process. The agent first queries a local Qdrant vector database that
indexes PubMed article embeddings. We constructed this vector store using LlamaIndex embeddings
of PubMed abstracts, enabling semantic search beyond keyword matching. However, due to time
constraints, the vector index was only partially populated (approximately 15 per cent of the PubMed
corpus). This partial coverage limited the standalone efectiveness of vector search—if the relevant
information was not in the indexed portion, the semantic query would fail.</p>
        <p>
          Therefore, the Researcher Agent employs a backof strategy: if the vector search yields insuficient
results or if additional diversity is needed, it falls back to the NCBI PubMed E-Utilities API to fetch
relevant articles via traditional keyword search. This hybrid approach combines the advantages of
dense semantic retrieval and classic lexical retrieval, which has been shown to improve recall in
biomedical question answering systems [
          <xref ref-type="bibr" rid="ref9">9</xref>
          ]. Specifically, semantic search helps retrieve conceptually
relevant documents that lexical search might miss (for example, retrieving an article about "myocardial
infarction" for a query on "heart attack"), while the PubMed API (a BM25-based engine) ensures
up-todate and high-precision results for exact keyword matches. Similar hybrid strategies combining BM25
with transformer-based dense retrieval have proven efective in past BioASQ challenges [
          <xref ref-type="bibr" rid="ref9">9</xref>
          ]. Figure 2
illustrates a screenshot of the AQAMS question-answering system application.
        </p>
        <p>In our implementation, the Researcher Agent also had access to a small repository of few-shot example
queries to aid prompt formulation. If a new question was similar to a previously solved question, the
agent could adapt a known efective query pattern (e.g., adding specific MeSH terms or synonyms)
based on those examples. This served as a form of prompt enhancement for retrieval, inspired by
recent prompt-based retrieval augmentation techniques [36]. Once relevant documents and snippets
are retrieved, the pipeline enters the second stage (Phase A+), where the Writer Agent generates the
answers. The Writer Agent is built on a transformer-based large language model (specifically, OpenAI
GPT-3.5 and GPT-4, accessed via API) with carefully designed prompt templates. Prompt engineering
was crucial: we created structured prompts that provide the question, a selection of top-ranked snippets
(with citations), and explicit instructions for the answer format. The agent was instructed to produce
two outputs: an exact answer and an ideal answer. For exact answers, the prompt template varied based
on question type.</p>
        <p>We found that including a few demonstrations question-answer pairs in the prompt (few-shot
prompting) further improved the consistency of the answers, consistent with findings that GPT models
can follow examples to produce well-formatted outputs [35]. The ideal answer prompt was designed to
elicit a comprehensive yet focused summary. It typically included a prefix such as "Using the information
from the above snippets, write a detailed answer:" and instructed the model not to merely copy text but to
synthesize and explain in a cohesive paragraph. The model was not allowed to cite external knowledge
not found in the snippets, thereby minimizing unsupported statements. By providing relevant snippets
as context, we essentially grounded the language model’s generation in real biomedical evidence, an
approach akin to retrieval-augmented generation that reduces hallucination [37]. The outputs from the
Writer Agent (exact and ideal answers) were then returned and displayed to the user or evaluator. We
deployed AQAMS via a Streamlit web interface for ease of use, supporting both single-question queries
and batch processing.</p>
      </sec>
      <sec id="sec-4-2">
        <title>4.2. AQAMS2: Phase B System</title>
        <p>AQAMS2 was developed for BioASQ 13B Phase B, where the challenge is to generate answers strictly
from the given snippets without any external retrieval. Since all necessary information is provided in
the input, AQAMS2 focuses on understanding and organizing the snippet content to produce correct
answers. The system maintains the same overall two-agent architecture, but the roles of the agents are
adjusted.</p>
        <p>The Researcher Agent in AQAMS2 does not perform document retrieval; instead, it conducts
biomedical named entity recognition (NER) and concept identification on the provided snippets. We integrated
a fine-tuned biomedical NER model (based on a RoBERTa transformer) to tag entities such as diseases,
drugs, and genes in the snippets. These recognized entities were then optionally mapped to standard
concepts in the UMLS (Unified Medical Language System) ontology. For example, if "heart attack" is
detected in a snippet, it would be mapped to the UMLS concept for "myocardial infarction (C0027051)".</p>
        <p>
          This concept mapping (entity linking) is not part of the output but is used internally to cluster
and reason about the information. Linking textual mentions to unique identifiers allows the system
to recognize when diferent snippets mention the same underlying concept through synonyms or
abbreviations [
          <xref ref-type="bibr" rid="ref10">10</xref>
          ]. This alignment supports the Writer Agent in avoiding redundancy and ensuring
consistency in the final answer. Prior work has shown that such ontology mappings enable unified
reasoning over biomedical texts with varied terminology [38].
        </p>
        <p>The Writer Agent in AQAMS2 takes as input the question and the set of provided snippets (augmented
with any metadata from the Researcher, such as recognized entities or identified key facts). The prompt
template is structured to encourage evidence-supported generation. In BioASQ Phase B, systems can
output three fields: the exact answer, the ideal answer, and an optional "supported answer" which
provides supporting evidence references. We utilized this by having the Writer Agent produce a
supported answer that explicitly cites snippet indices. Specifically, after generating an exact answer
(e.g., a specific drug name) and an ideal answer (a short paragraph explanation), the model is prompted
to generate a series of sentences like: "[Answer] This conclusion is supported by [Snippet 2], which
states that ’...’", incorporating snippet identifiers. Figure 3 illustrates one of the prompts used.</p>
        <p>The exact and ideal answer generation in AQAMS2 uses similar prompt techniques as in AQAMS, with
adjustments for the available input. Because the input snippets already contain the relevant information,
the Writer Agent’s task is closer to summarization or extraction. For factoid or list questions, the model
is prompted to identify the specific entities in the snippets that answer the question (benefiting from
the NER results). For yes/no questions, the model looks for afirmative or negative language in snippets
(e.g., "does not afect survival" indicates a "No") and any consensus among snippets.</p>
        <p>The ideal answers in Phase B are typically shorter than in Phase A+, since there is a limited, focused
context to draw from. We tuned the prompt to avoid verbosity and not introduce extraneous information
beyond the snippets.</p>
        <p>We employed diverse prompting strategies ranging from simple task-specific instruction prompts and
chain-of-thought prompts to multi-type answer extraction prompts. Our approach utilizes a complex
conditional prompt incorporating multiple advanced techniques: few-shot learning elements
(typespecific examples and instructions), chain-of-thought (CoT) reasoning (structured decision process),
template-based prompting (conditional logic based on question type), and constrained generation
prompting (strict output format requirements).</p>
        <p>This prompting technique demonstrates ensemble-like logic, as the conditional branching mimics
ensemble approaches by employing diferent strategies for each question type. This methodology
represents what Hu et al. describe as a task-specific prompt framework that includes baseline prompts
with task description and format specification, annotation guideline-based prompts, and error
analysisbased instructions [39]. The conditional structure for diferent question types (factoid, list, yes/no)
implements what Alhamzawi et al. classify as "heuristic prompts," utilizing domain knowledge and
logical reasoning to guide the model’s output.</p>
        <p>AQAMS2 was also deployed with a Streamlit interface for consistency, allowing batch processing
of Phase B questions. The interface displays the input snippets and the system’s outputs (exact, ideal,
supported answers). This mirrors a real-world scenario where a user might ask a question and want
to know not just the response, but also which snippets support it. This transparency is important in
biomedical question answering, as users need to trust and verify the source of an answer. Figure 4
illustrates the output of the AQAMS2 system.</p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>5. AQAMS and AQAMS2 Results</title>
      <p>Both AQAMS and AQAMS2 were evaluated on the oficial BioASQ 13B test sets. We report performance
on all batches of the phases in which our systems participated: Batches 3 and 4 of Phases A and A+ for
AQAMS, and Batches 3 and 4 of Phase B for AQAMS2. Tables 1–5 summarize the evaluation metrics as
provided by the BioASQ organizers’ evaluation tool.</p>
      <sec id="sec-5-1">
        <title>5.1. Phase A Results (AQAMS)</title>
        <p>In Phase A, the results were suboptimal due to incomplete vector database indexing (15% of PubMed
corpus) and limitations of the PubMed API. These challenges significantly impacted downstream snippet
extraction efectiveness, as the pool of candidate abstracts was inadequate for comprehensive retrieval.</p>
      </sec>
      <sec id="sec-5-2">
        <title>5.2. Phase A+ Results (AQAMS)</title>
        <p>AQAMS demonstrated heterogeneous performance across question types, with rankings varying from
upper to middle tiers depending on task complexity. Yes/No questions showed substantial improvement
(81.8% → 92.3% accuracy), achieving competitive performance in Batch 4 (2nd-5th position). This
supports the multi-agent architecture’s efectiveness in binary classification tasks. Factoid questions
exhibited notable adaptation with 173% relative improvement between batches (15.0% → 40.9% strict
accuracy), progressing from lower-middle to upper-middle tier performance. However, list questions
maintained consistent middle-tier performance, while ideal answers showed performance decline,
indicating synthesis limitations in the Writer Agent.</p>
      </sec>
      <sec id="sec-5-3">
        <title>5.3. Phase B Results (AQAMS2)</title>
        <p>AQAMS2 demonstrated substantially improved performance compared to Phase A+, with notable
enhancements across all evaluation metrics. Yes/No questions achieved the maximum accuracy of
95.45% in Batch 3, tying for first place with approximately 30% of participating systems, while achieving
4th place overall among teams when averaged across all question types. List questions showed strong
performance in Batch 3 (63.1% F-measure, 3rd-5th position), providing evidence consistent with the
efectiveness of NER integration within the Researcher Agent, though formal ablation studies would be
needed to establish causality. Factoid questions exhibited considerable adaptation capability (30.0% →
54.5%, +82% relative improvement). Ideal answers showed consistent upper-tier performance with 183%
improvement over Phase A+ (18.4% vs 6.5% ROUGE-2 F1).</p>
      </sec>
    </sec>
    <sec id="sec-6">
      <title>6. Analysis and Discussion</title>
      <sec id="sec-6-1">
        <title>6.1. Prompt Engineering and Few-Shot Integration</title>
        <p>Our Writer Agent employs a hierarchical prompt structure that adapts to question types and integrates
contextually relevant few-shot examples. The system-level prompt establishes the biomedical expert
persona and output format rules, while question-specific templates provide targeted instructions.</p>
        <p>Example Phase A+ Prompt Template (Yes/No Questions):
Q u e s t i o n : { q u e s t i o n }
Type : y e s n o
R e l e v a n t PubMed P u b l i c a t i o n s ( S n i p p e t s ) :
{ r a n k e d _ s n i p p e t s _ w i t h _ p m i d s }
I n s t r u c t i o n s : B a s e d s t r i c t l y on t h e p r o v i d e d e v i d e n c e , a n s w e r ’ y e s ’
o r ’ no ’ .</p>
        <p>I f e v i d e n c e i s a m b i g u o u s o r i n s u f f i c i e n t , d e f a u l t t o ’ no ’ .
R e s p o n d w i t h JSON : { " e x a c t _ a n s w e r " : " y e s | no " , " i d e a l _ a n s w e r " : " . . . " }</p>
        <p>Few-Shot Integration Mechanism: Our few-shot integration operates through dynamic example
insertion during chat completion generation. The system constructs message sequences by: (1) placing
the system prompt first, (2) inserting retrieved few-shot examples as alternating user-assistant message
pairs, and (3) appending the current question as the final user message.</p>
        <p>The generate_chat_completion function receives few-shot examples as a parameter and
automatically integrates them into the conversation flow before processing the current query. For example,
if a factoid question about drug mechanisms is processed, the system retrieves similar question-answer
pairs from our Qdrant vector store and inserts them as demonstration examples, enabling the model to
learn the expected response format and reasoning patterns for that specific question type.</p>
        <p>This approach provides contextual learning without requiring model fine-tuning, allowing the LLM
to adapt its behavior based on relevant historical examples.</p>
      </sec>
      <sec id="sec-6-2">
        <title>6.2. Architectural Validation and Context Quality Efects</title>
        <p>The comparative performance between phases provides empirical support for our multi-agent
architecture. The 183% improvement in ideal answers from Phase A+ to Phase B indicates that agentic
coordination performs more efectively with high-quality, focused context compared to broad retrieval
approaches. This observation aligns with our theoretical framework wherein traditional NLP pipelines
implement static processing sequences, while our agentic framework enables contextual
decisionmaking where specialized agents adapt strategies based on question characteristics.</p>
      </sec>
      <sec id="sec-6-3">
        <title>6.3. NER Integration Success as Tool vs. Agent</title>
        <p>Phase B’s improved list performance (85% enhancement: 31.3% → 57.9% F-measure) supports our
architectural decision to integrate biomedical NER as a specialized tool within the Researcher Agent
rather than implementing a separate agent. This design adheres to the principle that agents function as
autonomous decision-making entities, while tools serve as functional components activated by agents
based on contextual requirements. NER as a specialized tool could be integrated into the Phase A system
as well to potentially improve performance. We intentionally did not implement this enhancement
during the challenge in order to compare performance with and without NER integration, providing a
controlled evaluation of the tool’s impact on system efectiveness.</p>
      </sec>
      <sec id="sec-6-4">
        <title>6.4. Cross-Phase Architectural Insights</title>
        <p>Retrieval Dependency: Phase A performance indicates that agentic architectures exhibit critical
dependency on knowledge base completeness. The incomplete vector indexing (15% of PubMed) created
a retrieval bottleneck that constrained downstream performance.</p>
        <p>Context Synthesis Performance: The 3× improvement in ROUGE-2 F1 (0.1888 vs. 0.0616) indicates
that agent coordination performs efectively when synthesizing multiple information sources within
curated contexts.</p>
        <p>Adaptation Capability: The substantial factoid improvements in both phases (173% in A+, 82% in B)
demonstrate the system’s adaptability and learning capacity—a characteristic advantage of distributed
decision-making architectures.</p>
      </sec>
      <sec id="sec-6-5">
        <title>6.5. Competitive Positioning and Limitations</title>
        <p>Our systems achieved competitive rankings across most evaluation metrics. AQAMS maintained
consistent performance in the upper tier for yes/no questions and middle-tier performance in other
categories. AQAMS2 demonstrated balanced performance across all question types, ranking within the
upper quartile with particular efectiveness in structured extraction tasks.</p>
        <p>Performance Limitations: The declining ideal answer performance in Phase A+ indicates challenges
in answer synthesis when processing potentially irrelevant or incomplete retrieval results. Additionally,
the Phase B list performance decline between batches (63.1% → 52.8%) suggests potential overfitting or
batch-specific adaptation challenges.</p>
      </sec>
      <sec id="sec-6-6">
        <title>6.6. Key Findings</title>
        <p>Our multi-agent approach demonstrates competitive performance that suggests potential benefits of
coordinated agent interaction for biomedical question answering tasks. The comparative performance
between Phase A+ and Phase B indicates that the architecture performs more efectively with
highquality, focused context compared to open-domain retrieval scenarios, though the observed diferences
could be attributed to multiple factors including task complexity and data availability. AQAMS2 achieved
a competitive position overall among participating teams with notable variation in performance (4th
position in Batch 3, declining in Batch 4). While this ranking demonstrates the viability of the multi-agent
approach, the results indicate that more development is needed to achieve performance comparable to
leading systems.</p>
      </sec>
    </sec>
    <sec id="sec-7">
      <title>7. Future Work</title>
      <p>There are several lines of work to explore for improving both AQAMS and AQAMS2 in future editions:</p>
      <sec id="sec-7-1">
        <title>7.1. Complete and Enhanced Indexing</title>
        <p>The priority for AQAMS is to finish populating the PubMed vector index and possibly update it with the
latest literature. A full corpus semantic index would improve recall significantly. In addition, integrating
a neural re-ranker could help sort the retrieved snippets by relevance before passing to the Writer
Agent.</p>
      </sec>
      <sec id="sec-7-2">
        <title>7.2. Better Entity Handling and Answer Post-processing</title>
        <p>Our use of NER and UMLS was a step towards deeper understanding. We plan to build on this by
implementing an entity-based post-processor. For example, after the Writer Agent produces an answer,
we could verify if all UMLS-linked concepts in the snippets that seem crucial to the question are reflected
in the answer.</p>
      </sec>
      <sec id="sec-7-3">
        <title>7.3. Long-term Agentic Vision</title>
        <p>Based on our results analysis, we identify key architectural improvements that extend beyond traditional
NLP pipeline enhancements:</p>
        <p>Multi-Source Validation: Developing cross-validation mechanisms between Qdrant and PubMed
results to ensure retrieval robustness and reduce dependency on single knowledge sources.</p>
        <p>Context Quality Assessment: Implementing agents capable of evaluating context quality and
dynamically adjusting retrieval strategies, addressing the critical finding that agentic coordination
excels with high-quality, focused context rather than broad retrieval.</p>
        <p>Beyond these immediate improvements, we plan to continue advancing our agentic systems approach
to question answering, with the long-term goal of developing increasingly autonomous systems that
can independently reason, validate, and refine their responses with minimal human intervention.</p>
        <p>The empirical evidence from our Phase B results—demonstrating 183% improvement in ideal answers
through focused context coordination—provides methodological support for this research direction. We
believe these developments are important for building reliable question answering systems that can
assist researchers and clinicians in navigating the expanding biomedical literature.</p>
      </sec>
    </sec>
    <sec id="sec-8">
      <title>Declaration on Generative AI</title>
      <p>During the preparation of this work, the author(s) used GPT-4 in order to: Grammar and spelling check.
After using these tool(s)/service(s), the author(s) reviewed and edited the content as needed and take(s)
full responsibility for the publication’s content.
org/Vol-3740/paper-16.pdf.
[19] M. Jeong, J. Sohn, M. Sung, J. Kang, Improving medical reasoning through retrieval and
selfreflection with retrieval-augmented large language models, Bioinformatics 40 (2024) i119 – i129.
doi:10.1093/bioinformatics/btae238.
[20] L. Stuhlmann, M. A. Saxer, J. Fürst, Eficient and reproducible biomedical question answering using
retrieval augmented generation, 2025. URL: https://arxiv.org/abs/2505.07917. arXiv:2505.07917.
[21] S. Ateia, U. Kruschwitz, Can open-source LLMs compete with commercial models? exploring
the few-shot performance of current GPT models in biomedical tasks, in: CEUR Workshop
Proceedings, volume 3740, 2024, p. paper 7. URL: https://ceur-ws.org/Vol-3740/paper-07.pdf.
[22] R. Bramley, et al., Notes on the data quality of bibliographic records from the MEDLINE
database, Database: The Journal of Biological Databases and Curation 2023 (2023) baad070.
URL: https://academic.oup.com/database/article/doi/10.1093/database/baad070/7231777. doi:10.
1093/database/baad070.
[23] E. Sayers, A general introduction to the e-utilities, in: E. Sayers (Ed.), Entrez Programming
Utilities Help [Internet], updated 2022 nov 17 ed., National Center for Biotechnology Information
(US), 2009, pp. 1–15. URL: https://www.ncbi.nlm.nih.gov/books/NBK25497/, available from: https:
//www.ncbi.nlm.nih.gov/books/NBK25497/.
[24] S. Vatsal, et al., A survey of prompt engineering methods in large language models for diferent
NLP tasks, Department of Computer Science New York University (2024). URL: https://arxiv.org/
html/2407.12994v1.
[25] G. Marvin, N. Hellen, D. Jjingo, J. Nakatumba-Nabende, Prompt engineering in large language
models, in: I. J. Jacob, S. Piramuthu, P. Falkowski-Gilski (Eds.), Data Intelligence and Cognitive
Informatics, Springer Nature Singapore, Singapore, 2024, pp. 387–402.
[26] X. Hu, Y. Chen, L. Zhang, R. Wang, Q. Liu, Task-specific prompt frameworks for biomedical
text mining: A systematic review, Journal of Biomedical Informatics 141 (2024) 104494. URL:
https://pubmed.ncbi.nlm.nih.gov/38281112/.
[27] B. Alshaikhdeeb, et al., Biomedical named entity recognition: A review, 2016. URL: https://www.</p>
      <p>researchgate.net/publication/311917426_Biomedical_Named_Entity_Recognition_A_Review.
[28] N. Perera, et al., Named entity recognition and relation detection for biomedical information
extraction, 2020. URL: https://pubmed.ncbi.nlm.nih.gov/32984300/.
[29] D. Molla, et al., Named entity recognition for question answering, 2006. URL: https://aclanthology.</p>
      <p>org/U06-1009.pdf.
[30] M. Monajatipoor, LLMs in biomedical: A study on named entity recognition, arXiv preprint
arXiv:2404.07376 (2024). URL: https://arxiv.org/abs/2404.07376, preprint.
[31] H. Park, J. Son, J. Min, J. Choi, Selective UMLS knowledge infusion for biomedical
question answering, Scientific Reports 13 (2023). URL: https://www.researchgate.net/publication/
373519004_Selective_UMLS_knowledge_infusion_for_biomedical_question_answering. doi:10.
1038/s41598-023-41423-8.
[32] Y. Du, J. Yan, Y. Lu, Y. Zhao, X. Jin, Improving biomedical question answering by data augmentation
and model weighting, IEEE/ACM Transactions on Computational Biology and Bioinformatics PP
(2022) 1–1. doi:10.1109/TCBB.2022.3171388.
[33] Q. Jin, Z. Yuan, G. Xiong, Q. Yu, H. Ying, C. Tan, M. Chen, S. Huang, X. Liu, S. Yu, Biomedical
question answering: A survey of approaches and challenges, ACM Computing Surveys 55 (2022).</p>
      <p>URL: http://dx.doi.org/10.1145/3490238. doi:10.1145/3490238.
[34] W. Zhao, Z. Deng, S. Yadav, P. S. Yu, Heterogeneous knowledge grounding for medical question
answering with retrieval augmented large language model, in: Companion Proceedings of the ACM
Web Conference 2024, WWW ’24, Association for Computing Machinery, New York, NY, USA, 2024,
p. 1590–1594. URL: https://doi.org/10.1145/3589335.3651941. doi:10.1145/3589335.3651941.
[35] T. B. Brown, B. Mann, N. Ryder, M. Subbiah, J. Kaplan, P. Dhariwal, A. Neelakantan, P. Shyam,
G. Sastry, A. Askell, S. Agarwal, A. Herbert-Voss, G. Krueger, T. Henighan, R. Child, A. Ramesh,
D. M. Ziegler, J. Wu, C. Winter, C. Hesse, M. Chen, E. J. Sigler, M. Litwin, S. Gray, B. Chess,
J. Clark, C. Berner, S. McCandlish, A. Radford, I. Sutskever, D. Amodei, Language models are
few-shot learners, Neural Information Processing Systems 33 (2020) 1877 – 1901. URL: https:
//proceedings.neurips.cc/paper/2020/file/1457c0d6bfcb4967418bfb8ac142f64a-Paper.pdf.
[36] Y. Zhang, D. Merrill, K. Logan, G. Ananiadou, Optimizing biomedical information retrieval with a
keyword frequency-driven prompt enhancement strategy, BMC Bioinformatics 25 (2024). URL:
https://bmcbioinformatics.biomedcentral.com/articles/10.1186/s12859-024-05123-4.
[37] P. Lewis, E. Perez, A. Piktus, F. Petroni, V. Karpukhin, N. Goyal, H. Küttler, M. Lewis,
W.t. Yih, T. Rocktäschel, S. Riedel, D. Kiela, Retrieval-augmented generation for
knowledgeintensive NLP tasks, in: H. Larochelle, M. Ranzato, R. Hadsell, M. Balcan, H. Lin
(Eds.), Advances in Neural Information Processing Systems, volume 33, Curran Associates,
Inc., 2020, pp. 9459–9474. URL: https://proceedings.neurips.cc/paper_files/paper/2020/file/
6b493230205f780e1bc26945df7481e5-Paper.pdf.
[38] E. Jimenez-Ruiz, B. C. Grau, I. Horrocks, R. Berlanga, Logic-based assessment of the compatibility
of UMLS ontology sources, Journal of Biomedical Semantics 2 (2011) S2. URL: https://jbiomedsem.
biomedcentral.com/articles/10.1186/2041-1480-2-S1-S2. doi:10.1186/2041-1480-2-S1-S2.
[39] Y. Hu, Q. Chen, J. Du, X. Peng, V. K. Keloth, X. Zuo, Y. Zhou, Z. Li, X. Jiang, Z. Lu, K. Roberts, H. Xu,
Improving large language models for clinical named entity recognition via prompt engineering,
Journal of the American Medical Informatics Association 31 (2024) 1812–1820. doi:10.1093/
jamia/ocad259. arXiv:2303.16416, published online January 27, 2024.</p>
    </sec>
  </body>
  <back>
    <ref-list>
      <ref id="ref1">
        <mixed-citation>
          [1]
          <string-name>
            <given-names>K. A.</given-names>
            <surname>Hambarde</surname>
          </string-name>
          ,
          <string-name>
            <given-names>H.</given-names>
            <surname>Proenca</surname>
          </string-name>
          ,
          <article-title>Information retrieval: recent advances and beyond</article-title>
          ,
          <source>IEEE Access 11</source>
          (
          <year>2023</year>
          )
          <fpage>76581</fpage>
          -
          <lpage>76604</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref2">
        <mixed-citation>
          [2]
          <string-name>
            <given-names>X.</given-names>
            <surname>Cai</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C.</given-names>
            <surname>Wang</surname>
          </string-name>
          ,
          <string-name>
            <given-names>Q.</given-names>
            <surname>Long</surname>
          </string-name>
          ,
          <string-name>
            <given-names>Y.</given-names>
            <surname>Zhou</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Xiao</surname>
          </string-name>
          ,
          <article-title>Dataset distillation for domain LLM training</article-title>
          ,
          <source>arXiv preprint arXiv:2501.15108</source>
          (
          <year>2025</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref3">
        <mixed-citation>
          [3]
          <string-name>
            <given-names>A.</given-names>
            <surname>Nentidis</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Krithara</surname>
          </string-name>
          , G. Paliouras,
          <string-name>
            <given-names>M.</given-names>
            <surname>Krallinger</surname>
          </string-name>
          ,
          <string-name>
            <given-names>L. G.</given-names>
            <surname>Sanchez</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Lima</surname>
          </string-name>
          ,
          <string-name>
            <given-names>E.</given-names>
            <surname>Farre</surname>
          </string-name>
          ,
          <string-name>
            <given-names>N.</given-names>
            <surname>Loukachevitch</surname>
          </string-name>
          ,
          <string-name>
            <given-names>V.</given-names>
            <surname>Davydova</surname>
          </string-name>
          , E. Tutubalina, Bioasq at clef2024:
          <article-title>The twelfth edition of the large-scale biomedical semantic indexing and question answering challenge</article-title>
          , in: N.
          <string-name>
            <surname>Goharian</surname>
            ,
            <given-names>N.</given-names>
          </string-name>
          <string-name>
            <surname>Tonellotto</surname>
            ,
            <given-names>Y.</given-names>
          </string-name>
          <string-name>
            <surname>He</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          <string-name>
            <surname>Lipani</surname>
            ,
            <given-names>G.</given-names>
          </string-name>
          <string-name>
            <surname>McDonald</surname>
            ,
            <given-names>C.</given-names>
          </string-name>
          <string-name>
            <surname>Macdonald</surname>
          </string-name>
          , I. Ounis (Eds.),
          <source>Advances in Information Retrieval</source>
          , Springer Nature Switzerland, Cham,
          <year>2024</year>
          , pp.
          <fpage>490</fpage>
          -
          <lpage>497</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref4">
        <mixed-citation>
          [4]
          <string-name>
            <given-names>Q.</given-names>
            <surname>Jin</surname>
          </string-name>
          ,
          <string-name>
            <given-names>Z.</given-names>
            <surname>Yuan</surname>
          </string-name>
          ,
          <string-name>
            <given-names>G.</given-names>
            <surname>Xiong</surname>
          </string-name>
          ,
          <string-name>
            <given-names>Q.</given-names>
            <surname>Yu</surname>
          </string-name>
          ,
          <string-name>
            <given-names>H.</given-names>
            <surname>Ying</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C.</given-names>
            <surname>Tan</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Chen</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Huang</surname>
          </string-name>
          ,
          <string-name>
            <given-names>X.</given-names>
            <surname>Liu</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Yu</surname>
          </string-name>
          ,
          <article-title>Biomedical question answering: A survey of approaches and challenges</article-title>
          ,
          <source>ACM Computing Surveys</source>
          <volume>55</volume>
          (
          <year>2023</year>
          )
          <volume>35</volume>
          :
          <fpage>1</fpage>
          -
          <lpage>35</lpage>
          :
          <fpage>36</fpage>
          . doi:
          <volume>10</volume>
          .1145/3490238.
        </mixed-citation>
      </ref>
      <ref id="ref5">
        <mixed-citation>
          [5]
          <string-name>
            <given-names>S.</given-names>
            <surname>Sivarajkumar</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Kelley</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Samolyk-Mazzanti</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Visweswaran</surname>
          </string-name>
          ,
          <string-name>
            <given-names>Y.</given-names>
            <surname>Wang</surname>
          </string-name>
          ,
          <article-title>An empirical evaluation of prompting strategies for large language models in zero-shot clinical natural language processing: Algorithm development and validation study</article-title>
          ,
          <source>JMIR Med Inform</source>
          <volume>12</volume>
          (
          <year>2024</year>
          )
          <article-title>e55318</article-title>
          . URL: https://medinform.jmir.org/
          <year>2024</year>
          /1/e55318. doi:
          <volume>10</volume>
          .2196/55318.
        </mixed-citation>
      </ref>
      <ref id="ref6">
        <mixed-citation>
          [6]
          <string-name>
            <given-names>A.</given-names>
            <surname>Nentidis</surname>
          </string-name>
          ,
          <string-name>
            <given-names>G.</given-names>
            <surname>Katsimpras</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Krithara</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Krallinger</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Rodríguez-Ortega</surname>
          </string-name>
          ,
          <string-name>
            <given-names>E.</given-names>
            <surname>Rodriguez-López</surname>
          </string-name>
          ,
          <string-name>
            <given-names>N.</given-names>
            <surname>Loukachevitch</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Sakhovskiy</surname>
          </string-name>
          ,
          <string-name>
            <given-names>E.</given-names>
            <surname>Tutubalina</surname>
          </string-name>
          ,
          <string-name>
            <given-names>D.</given-names>
            <surname>Dimitriadis</surname>
          </string-name>
          , G. Tsoumakas,
          <string-name>
            <given-names>G.</given-names>
            <surname>Giannakoulas</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Bekiaridou</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Samaras</surname>
          </string-name>
          , et al.,
          <source>Overview of BioASQ</source>
          <year>2025</year>
          :
          <article-title>The thirteenth BioASQ challenge on large-scale biomedical semantic indexing and question answering</article-title>
          , in: J.
          <string-name>
            <surname>C. de Albornoz</surname>
            ,
            <given-names>J.</given-names>
          </string-name>
          <string-name>
            <surname>Gonzalo</surname>
            ,
            <given-names>L.</given-names>
          </string-name>
          <string-name>
            <surname>Plaza</surname>
          </string-name>
          ,
          <string-name>
            <surname>A. G. S. de Herrera</surname>
            ,
            <given-names>J.</given-names>
          </string-name>
          <string-name>
            <surname>Mothe</surname>
            ,
            <given-names>F.</given-names>
          </string-name>
          <string-name>
            <surname>Piroi</surname>
            ,
            <given-names>P.</given-names>
          </string-name>
          <string-name>
            <surname>Rosso</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          <string-name>
            <surname>Spina</surname>
          </string-name>
          , G. Faggioli, N. Ferro (Eds.),
          <source>Experimental IR Meets Multilinguality, Multimodality, and Interaction. Proceedings of the Sixteenth International Conference of the CLEF Association (CLEF</source>
          <year>2025</year>
          ),
          <year>2025</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref7">
        <mixed-citation>
          [7]
          <string-name>
            <given-names>A.</given-names>
            <surname>Nentidis</surname>
          </string-name>
          ,
          <string-name>
            <given-names>G.</given-names>
            <surname>Katsimpras</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Krithara</surname>
          </string-name>
          ,
          <string-name>
            <surname>G.</surname>
          </string-name>
          <article-title>Paliouras, Overview of BioASQ Tasks 13b and Synergy13 in CLEF2025</article-title>
          , in: G. Faggioli,
          <string-name>
            <given-names>N.</given-names>
            <surname>Ferro</surname>
          </string-name>
          ,
          <string-name>
            <given-names>P.</given-names>
            <surname>Rosso</surname>
          </string-name>
          , D. Spina (Eds.),
          <source>CLEF 2025 Working Notes</source>
          ,
          <year>2025</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref8">
        <mixed-citation>
          [8]
          <string-name>
            <given-names>G.</given-names>
            <surname>Tsatsaronis</surname>
          </string-name>
          , et al.,
          <article-title>An overview of the BIOASQ large-scale biomedical semantic indexing and question answering competition</article-title>
          ,
          <source>BMC Bioinformatics</source>
          (
          <year>2015</year>
          ). URL: https://bmcbioinformatics. biomedcentral.com/articles/10.1186/s12859-015-0564-6. doi:
          <volume>10</volume>
          .1186/s12859-015-0564-6.
        </mixed-citation>
      </ref>
      <ref id="ref9">
        <mixed-citation>
          [9]
          <string-name>
            <given-names>A.</given-names>
            <surname>Nentidis</surname>
          </string-name>
          ,
          <string-name>
            <given-names>G.</given-names>
            <surname>Katsimpras</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Krithara</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Lima-López</surname>
          </string-name>
          ,
          <string-name>
            <given-names>E.</given-names>
            <surname>Farré-Maduell</surname>
          </string-name>
          ,
          <string-name>
            <given-names>L.</given-names>
            <surname>Gasco</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Krallinger</surname>
          </string-name>
          , G. Paliouras, Overview of bioASQ 2023:
          <article-title>The eleventh bioASQ challenge on large-scale biomedical semantic indexing and question answering, Conference and Labs of the Evaluation Forum (</article-title>
          <year>2023</year>
          )
          <fpage>227</fpage>
          -
          <lpage>250</lpage>
          . doi:
          <volume>10</volume>
          .1007/978-3-
          <fpage>031</fpage>
          -42448-9_
          <fpage>19</fpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref10">
        <mixed-citation>
          [10]
          <string-name>
            <given-names>Q.</given-names>
            <surname>Jin</surname>
          </string-name>
          ,
          <string-name>
            <given-names>R.</given-names>
            <surname>Leaman</surname>
          </string-name>
          ,
          <string-name>
            <given-names>Z.</given-names>
            <surname>Lu</surname>
          </string-name>
          ,
          <article-title>Is ChatGPT a biomedical expert? - exploring the zero-shot performance of current GPT models in biomedical tasks</article-title>
          ,
          <source>arXiv preprint arXiv:2306.16108</source>
          (
          <year>2023</year>
          ). URL: https: //arxiv.org/abs/2306.16108.
        </mixed-citation>
      </ref>
      <ref id="ref11">
        <mixed-citation>
          [11]
          <string-name>
            <given-names>A.</given-names>
            <surname>Krithara</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Nentidis</surname>
          </string-name>
          ,
          <string-name>
            <given-names>K.</given-names>
            <surname>Bougiatiotis</surname>
          </string-name>
          , G. Paliouras,
          <string-name>
            <surname>BioASQ-QA</surname>
          </string-name>
          :
          <article-title>A manually curated corpus for Biomedical Question Answering</article-title>
          ,
          <source>Scientific Data</source>
          <volume>10</volume>
          (
          <year>2023</year>
          )
          <fpage>170</fpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref12">
        <mixed-citation>
          [12]
          <string-name>
            <given-names>M.</given-names>
            <surname>Wooldridge</surname>
          </string-name>
          , An Introduction to MultiAgent Systems, 2nd Edition | Wiley,
          <year>2009</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref13">
        <mixed-citation>
          [13]
          <string-name>
            <given-names>D.</given-names>
            <surname>Isern</surname>
          </string-name>
          ,
          <string-name>
            <given-names>D.</given-names>
            <surname>Sánchez</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Moreno</surname>
          </string-name>
          ,
          <article-title>Agents applied in health care: A review</article-title>
          ,
          <source>Int J Med Inform</source>
          <volume>79</volume>
          (
          <year>2010</year>
          )
          <fpage>145</fpage>
          -
          <lpage>166</lpage>
          . doi:
          <volume>10</volume>
          .1016/j.ijmedinf.
          <year>2010</year>
          .
          <volume>01</volume>
          .003.
        </mixed-citation>
      </ref>
      <ref id="ref14">
        <mixed-citation>
          [14]
          <string-name>
            <given-names>J.</given-names>
            <surname>Ferber</surname>
          </string-name>
          ,
          <string-name>
            <surname>Multi-Agent Systems</surname>
          </string-name>
          : An Introduction to Distributed Artificial Intelligence, Harlow : Addison-Wesley,
          <year>1998</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref15">
        <mixed-citation>
          [15]
          <string-name>
            <given-names>A.</given-names>
            <surname>Croatti</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Gabellini</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Montagna</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Ricci</surname>
          </string-name>
          ,
          <article-title>On the Integration of Agents and Digital Twins in Healthcare</article-title>
          ,
          <source>J Med Syst</source>
          <volume>44</volume>
          (
          <year>2020</year>
          )
          <article-title>161</article-title>
          . doi:
          <volume>10</volume>
          .1007/s10916-020-01623-5.
        </mixed-citation>
      </ref>
      <ref id="ref16">
        <mixed-citation>
          [16]
          <string-name>
            <given-names>R.</given-names>
            <surname>Stuart</surname>
          </string-name>
          , N. Peter,
          <string-name>
            <surname>Artificial Intelligence</surname>
            :
            <given-names>A Modern</given-names>
          </string-name>
          <string-name>
            <surname>Approach</surname>
          </string-name>
          , Hoboken, NJ,
          <year>2021</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref17">
        <mixed-citation>
          [17]
          <string-name>
            <given-names>H.</given-names>
            <surname>Zhang</surname>
          </string-name>
          , et al.,
          <article-title>Leveraging long context in retrieval augmented language models for medical question answering</article-title>
          ,
          <source>npj Digital Medicine</source>
          <volume>8</volume>
          (
          <year>2025</year>
          )
          <article-title>12</article-title>
          . URL: https://pubmed.ncbi.nlm.nih.gov/ 40316710/. doi:
          <volume>10</volume>
          .1038/s41746-025-01651-w.
        </mixed-citation>
      </ref>
      <ref id="ref18">
        <mixed-citation>
          [18]
          <string-name>
            <given-names>A.</given-names>
            <surname>Merker</surname>
          </string-name>
          , et al.,
          <source>Mibi at BioASQ</source>
          <year>2024</year>
          :
          <article-title>Retrieval-augmented generation for answering biomedical questions</article-title>
          ,
          <source>in: CEUR Workshop Proceedings</source>
          , volume
          <volume>3740</volume>
          ,
          <year>2024</year>
          , p.
          <fpage>paper</fpage>
          <lpage>16</lpage>
          . URL: https://ceur-ws.
        </mixed-citation>
      </ref>
    </ref-list>
  </back>
</article>