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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Embedding-Assisted Entity Resolution for Knowledge Graphs</article-title>
      </title-group>
      <contrib-group>
        <aff id="aff0">
          <label>0</label>
          <institution>Leipzig University</institution>
          ,
          <country country="DE">Germany</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>Entity Resolution (ER) is a main task for integrating di erent knowledge graphs in order to identify entities referring to the same real-world object. A promising approach is the use of graph embeddings for ER in order to determine the similarity of entities based on the similarity of their graph neighborhood. Previous work has shown that the use of graph embeddings alone is not su cient to achieve high ER quality. We therefore propose a more comprehensive ER approach for knowledge graphs called EAGER (E mbedding-Assisted Knowledge Graph E ntity Resolution) to exibly utilize both the similarity of graph embeddings and attribute values within a supervised machine learning approach and that can perform ER for multiple entity types at the same time. Furthermore, we comprehensively evaluate our approach on 19 benchmark datasets with di erently sized and structured knowledge graphs and use hypothesis tests to ensure statistical signi cance of our results. We also compare our approach with state-of-the-art ER solutions, where EAGER yields competitive results for shallow knowledge graphs but much better results for deeper knowledge graphs.</p>
      </abstract>
      <kwd-group>
        <kwd>Knowledge Graph</kwd>
        <kwd>Knowledge Graph Embedding</kwd>
        <kwd>Entity Resolution</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>Knowledge Graphs (KGs) store real-world facts in machine-readable form. This
is done by making statements about entities in triple form (entity; property;
value). For example the triple (Get Out, director, Jordan Peele) tells us
that the director of the movie "Get Out" is "Jordan Peele". Such structured
information can be used for a variety of tasks such as recommender systems,
question answering and semantic search. For many KG usage forms including
question answering it is bene cial to integrate KGs from di erent sources. An
integral part of this integration is entity resolution (ER), where the goal is to
nd entities which refer to the same real-world object.</p>
      <p>Existing ER systems mostly focus on matching entities of one speci c entity
type (e.g. publication, movie, customer etc.) and assume matched schemata for
this entity type. This proves challenging when trying to use these systems for ER
in KGs typically consisting of many entity types with heterogeneous attribute
(property) sets. See Figure 1 for an example showcasing the many di erent
challenges of this task, such as heterogeneous date representations ("1979-02-21"
vs. "21 Febuary 1979"), di ering URIs ("dbr:Jordan Peele" vs. "wd: Q3371986"),
schemata ("dbo:birthdate" vs. "wdt:P569") and overall information contained.</p>
      <p>DBpedia
"Get Out"^^xsd:String
dbo:Film</p>
      <p>rdf:type
rdfs:label</p>
      <p>dbr:Get_Out
dbo:starring</p>
      <p>dbo:director
dbr:Allison_Williams
rdfs:label
"Allison
Williams
(actress)"</p>
      <p>rdfs:label
dbo:birthDate "Jordan</p>
      <p>Peele"
1979-0221^^xsd:date</p>
      <p>Wikidata
wd:Q11424
wdt:P31</p>
      <p>rdfs:label
wd:Q25136235
wdt:P57 wdt:P161</p>
      <p>rdfs:label
wdt:P569
"Jordan</p>
      <p>Peele"
21 February 1979
"Get Out"^^xsd:String
wd:Q510970
rdfs:label
"Daniel</p>
      <p>Kaluuya"
dbr:Jordan_Peele
wd:Q3371986</p>
      <p>We observe there are entities of di erent types ( lm, director, actor) and
di erent attributes with heterogeneous value representations (e.g., birth date
values "1979-02-21" in DBpedia and "21 Febuary 1979" in Wikidata for two
matching director entities). Moreover, we see that matching entities such as
the movie "Get Out" have di erent URIs and di erently named edges referring
to properties and related entities, e.g. rdf:type vs. wdt:P31. These aspects
make a traditional schema (property) matching as a means to simplify ER very
challenging so that entity resolution for KGs should ideally not depend on it.
Given that URIs and property names may not show any similarity it becomes
apparent that the graph structure and related entities should be utilized in the
ER process, e.g., to consider the movie label and director to match movies.</p>
      <p>
        A promising way to achieve this in a generic manner, applicable to virtually
any entity type, is the use of graph embeddings. By encoding the entities of
the KGs into a low-dimensional space such approaches alleviate the obstacles
posed by the aforementioned KG heterogeneities. Capturing the topological and
semantic relatedness of entities in a geometric embedding space enables the
use of these embeddings as inputs for machine learning (ML) algorithms. The
performance of graph embedding approaches for ER has been recently studied
by Sun et. al [
        <xref ref-type="bibr" rid="ref28">28</xref>
        ]. However, as they point out, most approaches focus on re ning
the embedding process, while ER mostly consists of nding the nearest neighbors
in the embedding space. Hence, the use of graph embeddings has to be tailored
to the ER task for good e ectiveness. We build on the ndings of [
        <xref ref-type="bibr" rid="ref28">28</xref>
        ] and
investigate the usefulness of learned graph embeddings as input for ML classi ers
for entity resolution. While there are di erent settings for KG integration, such
as enhancing a given KG or KG fusion, we focus here on the simple ER setting,
i.e., nding matching entities in two data sources. The resulting match mappings
can then be used for applications such as question answering or as input for KG
fusion.
      </p>
      <p>
        In this paper, we propose and comprehensively evaluate the rst (to our
knowledge) graph embedding supported ER system named EAGER: Embedding
Assisted Knowledge Graph Entity Resolution. It uses both knowledge graph
embeddings and attribute similarities as inputs for an ML classi er for generic
entity resolution with several entity types. EAGER utilizes di erent kinds of
graph embeddings, speci cally the ones that performed best in [
        <xref ref-type="bibr" rid="ref28">28</xref>
        ], as well as
di erent ML classi ers. We comprehensively evaluate the match e ectiveness of
EAGER with using graph embeddings and attribute similarities either alone or in
combination for 19 datasets of varying size and structure. Some of these ER tasks
with multiple entity types from the movie domain have been newly developed
for this work. The evaluation also includes a comparison of EAGER with
stateof the-art ER approaches, namely Magellan [
        <xref ref-type="bibr" rid="ref16">16</xref>
        ] and DeepMatcher [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ]. All our
results are analyzed using hypothesis tests to ensure statistical signi cance of
our ndings.
      </p>
      <p>We rst discuss related work followed by an overview of EAGER. Section 4
describes the used datasets including the new benchmarks from the movie
domain. Our evaluation is presented in Section 5 and we conclude in Section 6.
2</p>
    </sec>
    <sec id="sec-2">
      <title>Related Work</title>
      <p>
        Entity resolution has attracted a signi cant amount of research, sometimes under
di erent names such as record linkage [
        <xref ref-type="bibr" rid="ref10 ref8">8,10</xref>
        ], link discovery [
        <xref ref-type="bibr" rid="ref26 ref29">29,26</xref>
        ] or
deduplication [
        <xref ref-type="bibr" rid="ref25">25</xref>
        ]. We focus on the discussion of the most related ER approaches. and
refer to surveys and books such as [
        <xref ref-type="bibr" rid="ref11 ref20 ref6">11,20,6</xref>
        ] for a more thorough overview.
Traditional ER approaches rely on learning distance- or similarity-based measures
and then use a threshold or classi er to decide about whether two entities are the
same. These classi ers can be unsupervised [
        <xref ref-type="bibr" rid="ref22 ref23">22,23</xref>
        ], supervised [
        <xref ref-type="bibr" rid="ref14 ref26">26,14</xref>
        ] or employ
active learning [
        <xref ref-type="bibr" rid="ref21 ref25">25,21</xref>
        ]. For example the Magellan Framework [
        <xref ref-type="bibr" rid="ref16">16</xref>
        ] provides
supervised ML classi ers and provides extensive guides for the entire ER process.
Recently, deep learning has seen some success in certain settings. DeepER [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ]
and DeepMatcher [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ] provide a variety of di erent architectures and among
other aspects, such as attribute similarities, use word embeddings as inputs for
these networks. Both frameworks have shown that especially for unstructured
textual data deep learning can outperform existing frameworks.
      </p>
      <p>
        Collective ER approaches try to overcome the limitations of the more
conventional attribute-based methods. This paradigm uses the relationships
between entities as additional information and in some cases even considers
previous matching decisions in the neighborhood. Bhattacharya and Getoor [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]
show that using the neighborhood of potential match candidates in addition
to attribute-based similarity is especially useful for data with many ambiguous
entities. SiGMa [
        <xref ref-type="bibr" rid="ref17">17</xref>
        ] uses an iterative graph propagation algorithm relying on
relationship information as well as attribute-based similarity between graphs to
integrate large-scale knowledge bases. Pershina et al. [
        <xref ref-type="bibr" rid="ref24">24</xref>
        ] propagate
similarities using Personalized PageRank and are able to align industrial size
knowledge graphs. Zhu et al. [
        <xref ref-type="bibr" rid="ref32">32</xref>
        ] reformulate entity resolution as multi-type graph
summarization problem and use attribute-based similarity as well as structural
similarity, i.e. connectivity patterns in the graph.
      </p>
      <p>
        More recently the use of graph embeddings has been shown promising for
the integration of KGs. An overview of currently relevant approaches that solely
rely on embedding techniques can be found in [
        <xref ref-type="bibr" rid="ref28">28</xref>
        ], some of these techniques
have been used in this work and will be discussed in more detail in Section
3.3. Knowledge graph embedding (KGE) models typically aim to capture the
relationship structure of each entity in latent vector representations in order to be
used for further downstream applications. For an overview of current knowledge
graph embedding approaches we refer the reader to a recent survey from Ali et
al. [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ].
      </p>
      <p>EAGER aims to combine the two generally separate ER approaches of graph
embedding techniques and traditional attribute- based methods for the
integration of KGs with multiple entity types without relying on additional schema
matching or any structural assumptions about the entities. Our extensive
evaluation for a large spectrum of KGs demonstrates the viability of the proposed
approach.
3</p>
    </sec>
    <sec id="sec-3">
      <title>Overview of EAGER</title>
      <p>
        In this section we present an overview of the EAGER approach for ER in
knowledge graphs and the speci c approaches and con gurations we will
evaluate. We start with a formal de nition of the ER problem and an overview of the
EAGER work ow. Subsequently we explain how we create the input vector for
our ML classi ers and conclude with a discussion of the prediction step.
KGs are constructed by triples in the form of (entity; property; value), where
property can be either a attribute property or a relationship and value a literal
or another entity, respectively. Therefore, a KG is a tuple KG = (E ; R; A; L; T ),
where E is the set of entities, A the set of attribute properties, R the set of
relationship properties, L the set of literals and T is the set of triples. We
distinguish attribute triples TA and relationship triples TR, where TA : E A
L are triples connecting entities and literals, e.g. (dbr:Jordan Peele, dbo:
birthDate, "1979-02-21") and TR : E R E connect entities, e.g. (dbr:
Get Out, dbo:director, dbr:Jordan Peele) as seen in Figure 1. Our goal is
to nd a mapping between entities of two KGs. More formally, we aim to nd
M = f(e1; e2) 2 E1 E2je1 e2g, where refers to the equivalence relation.
Furthermore, we assume we are provided with a subset of the mapped entities
MT M as training data, which is also sometimes referred to as seed alignment
in the literature.
The remaining chapter is dedicated to illustrate how our approach tackles
entity resolution in heterogeneous KGs. A schematical overview can be found in
Figure 2. Given two KGs KG1; KG2 and a set of initial matches MT we create
a feature vector for each match (e1; e2) 2 MT to train a machine learning
classi er. Additionally to the positive matches provided in MT we sample negative
examples by sampling random pairs (e1; e2) 2= MT to create a balanced set of
positive and negative examples. After the training step the classi er then acts as
an oracle to answer speci c alignment queries, i.e. entity pairs, in order to make
a prediction. In the following we present our approach in more detail.
Since schemata across di erent KGs may di er wildly, creating a schema
matching before ER in heterogeneous KGs is di cult and can introduce additional
sources for error. Keeping the focus on the matching process, we chose to
concatenate all attribute values of each entity into a single string and used 3 similarity
measures for comparisons: Levenshtein, Generalized Jaccard with an
Alphanumeric Tokenizer, which returns the longest strings of alphanumeric characters,
The code for EAGER and our experiments can be found in https://github.com/
jonathanschuchart/eager
and Trigrams with the Dice coe cient. The second part of the input vector
consists of KGEs. Given that the focus of this study lies not on the creation of
embeddings itself, our approach can take any entity embeddings that are
embedded in the same space. Since most KG embedding frameworks are not specialized
for ER, we use OpenEA which was developed by Sun et al. for their 2020
benchmark study[
        <xref ref-type="bibr" rid="ref28">28</xref>
        ]. It o ers a variety of embedding approaches and embeds entities
into the same space. Speci cally, we chose three of the best approaches of said
study, namely BootEA, MultiKE and RDGCN:
BootEA Sun et al. in 2018 [
        <xref ref-type="bibr" rid="ref27">27</xref>
        ] based their approach on the TransE model and
combined it with elaborate bootstrapping and negative sampling techniques to
improve performance. TransE aims to nd an embedding function that
minimizes jj (eh) + (r) (et)jj for any (eh; r; et) 2 TR. Bootstrapping is done
by additionally sampling likely matching entities (resampled every few epochs
based on the current model) in order to increase the e ective seed alignment
size. Additionally, negative relationship tuples are sampled and resampled
every few epochs based on the current model in order to improve the distinction
between otherwise similar entities. Since TransE is an unsupervised model, Sun
et al. proposed a new objective function which incorporates both the original
objective function of TransE and the likelihood of two entities from di erent
KGs matching.
      </p>
      <p>
        MultiKE In order to also incorporate more than just relational information,
Zhang et al. [
        <xref ref-type="bibr" rid="ref31">31</xref>
        ] proposed a exible model which combines di erent views on each
entity. Here, the name attribute, relations and all remaining attributes are
embedded separately, using pre-trained word2vec word embeddings [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ] for names
and a variation on TransE for relations. Attribute embeddings are obtained by
training a convolutional neural network taking the attribute and attribute value
as input. All three embedding vectors are then combined into a single uni ed
embedding space. In this approach the two knowledge graphs are treated as one
combined graph where entities from the seed alignment are treated as equal.
RDGCN Di erent to the aforementioned approaches, Wu et al. [
        <xref ref-type="bibr" rid="ref30">30</xref>
        ] proposed
a new technique using two constructed conventional graphs and the GCN model
by Kipf and Welling with highways. Instead of learning embeddings for entities
and relations within one graph, RDGCN constructs a primary entity graph and
a dual relationship graph in order to alternate the optimization process between
the two. That way, the relationship representations from the dual graph are used
to optimize the entity representations from the primal graph and vice versa by
applying a graph attention mechanism. As the actual neigborhood information
of each entity is not fully exploited in this case, Wu et al. showed that feeding
the resulting entity representations into a GCN can help signi cantly improve
the overall embedding quality.
      </p>
      <p>
        https://github.com/nju-websoft/OpenEA
As the aim of our study is to investigate to what degree combining entity
embeddings with attribute similarities is superior to using either on their own, we
present three di erent variants of our approach, that only di er in the
construction of their input vector: EAGERE contains solely the embeddings, EAGERA
consists exclusively of the attribute similarities and nally EAGERAkE which is
a concatenation of entity embeddings and attribute similarities. The respective
input vector is given to a classi er along with the seed alignment. In the
evaluation we achieved the best results using either a Multilayer Perceptron (MLP) [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ]
or Random Forest (RF) [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ], but any classi er can be used.
The trained classi er is presented with alignment queries, i.e. pairs of entities
that it will have to classify as match or non-match. Choosing these pairs is a
non-trivial question since exploring all possible pairs would lead to a quadratic
number of alignment queries relative to the KG size, which is not scalable to large
datasets. Traditionally, blocking strategies are used to reduce the number of pairs
by a linear factor. Due to the heterogeneous nature of KGs new strategies for
this problem have to be found. An alternative could be to use the embeddings to
nd a number of nearest neighbors, which is a scalable solution since the triangle
inequality in metric spaces can be exploited to reduce the number of comparisons
for the neighborhood search. Finding a good solution for this problem is however
out of scope for our study and in the experiments we therefore use the test data
to create prediction pairs, sampling negative examples randomly as done in the
training step. More on our experimental setup can be found in Section 5.1.
4
      </p>
    </sec>
    <sec id="sec-4">
      <title>Datasets</title>
      <p>
        To evaluate our approach we use multiple datasets that can generally be put
into two categories: rich and shallow graph datasets. The rich graph datasets
were presented in [
        <xref ref-type="bibr" rid="ref28">28</xref>
        ] and consist of samples from DBpedia (D), Wikidata (W)
and Yago (Y). Given their origin in web-scale KGs they o er a wide range of
relationships as well as entity types. The linking tasks include KG samples of
di erent density, size, as well as covering cross-lingual settings (EN-DE &amp;
ENFR).
      </p>
      <p>To investigate how the interplay of attribute similarities and graph
embeddings fares in settings with less dense KGs we created a new benchmark dataset
with multiple entity types. These KGs are taken from the movie domain, where
the gold standard was hand-labeled for the ve entity types Person, Movie,
TvSeries, Episode, Company. The movie datasets were created from three
sources containing information about movies and tv series: IMDB, TheMovieDB
https://www.imdb.com/
https://www.themoviedb.org/
and TheTVDB. We make the movie datasets publicly available for future
research at https://github.com/ScaDS/MovieGraphBenchmark. More details on
each of the datasets can be found in Table 1 and Table 2 respectively.
KD-Y YDGB 12685 23557 3206,,269318 17312,,711164 15,000 2712 2900 6608,,907603 16351,,110501 15,000
15EN-DE EN 215 286 47,676 83,755 81,988
DE 131 194 50,419 156,150 15,000 169 171 84,867
96 116 92,632 186,335 15,000
EN-FR EFRN 221607 430048 4407,,836344 6773,,116271 15,000 119636 128291 9860,,311182 6686,,787999 15,000
D-W WDBD 246113 847943 225913,,790980 648571,,806101 100,000 233198 736208 568186,,240537 847687,,211093 100,000
KD-Y YDGB 23827 33789 249040,,158188 572439,,076827 100,000 23310 23767 587665,,524675 584575,,012661 100,000
100EN-DE DENE 318916 425512 333356,,325490 575126,,765105 100,000 312730 312869 662229,,538985 576903,,274170 100,000
EN-FR EFRN 430000 456169 320598,,620875 449276,,762792 100,000 327897 346648 654691,,930921 540331,,932729 100,000
5</p>
    </sec>
    <sec id="sec-5">
      <title>Evaluation</title>
      <p>We discuss our results on the presented datasets, starting with a description
of the experiment setup, followed by the results on the shallow and rich graph
datasets, with a focus on investigating whether the use of attribute similarities
https://www.thetvdb.com/
in combination with knowledge graph embeddings is bene cial for the respective
setting. Furthermore we compare our approach with state-of-the-art frameworks.
5.1</p>
      <p>
        Setup
For the evaluation we use a 5-fold cross validation with a 7-2-1 split in accordance
with [
        <xref ref-type="bibr" rid="ref28">28</xref>
        ]: For each dataset pair the set of reference entity matches is divided into
70% testing, 20% training and 10% validation. For each split we sample negative
examples to create an equal share of positive and negative examples. The entire
process is repeated 5 times to create 5 di erent folds.
      </p>
      <p>
        For the OpenEA datasets the graph embeddings were computed using the
hyperparameters given by the study of [
        <xref ref-type="bibr" rid="ref28">28</xref>
        ]. For all other datasets the *-15K
parameter sets were used. For the classi ers, mostly scikit-learn's default
parameters were used, though Random Forest Classi er was used with 500 estimators
and MLP used two hidden layers of size 200 and 20. Furthermore, MLP was
trained using the Adam [
        <xref ref-type="bibr" rid="ref15">15</xref>
        ] optimizer with = 10 5.
5.2
      </p>
      <p>Results</p>
      <p>The results for all datasets are displayed in Table 3. In the bottom row
we display the average rank of each combination of input variant, embedding
approach and classi er which is a number between 1 and 14 (since there are 14
possible combinations), where 1 would mean this combination achieves the best
result for each dataset.</p>
      <p>For the movie datasets we can see that EAGERAkE with MultiKE performs
best, especially with the MLP classi er. This suggests that even for datasets with
relatively few relational information it can be bene cial to use knowledge graph
embeddings. However, it seems very dependent on the way these embeddings are
constructed in order for them to be useful with MultiKE being the only one of
the three embedding approaches to explicitly incorporate attribute data. This
also becomes apparent when comparing the results of EAGERE and EAGERA
where MultiKE performs best for EAGERE but is still clearly outperformed by
EAGERA.</p>
      <p>imdb-tmdb
imdb-tvdb
tmdb-tvdb</p>
      <p>Metric
fm
prec
rec</p>
      <p>Looking at the movie datasets in more detail as shown in Figure 3, we can
see that there is a di erence in performance depending on the entity type. In
most cases, EAGERAkE reaches an F-measure of over 90% for all entity types
showing that the approach is generic and able to achieve good match quality
for multiple heterogeneous entity types. Still there are some di erences between
the entity types. TVShows and Films generally perform worse than TVEpisodes
and Persons with especially the precision for Film standing out negatively. This
is especially pronounced in the IMDB-TMDB and IMDB-TVDB datasets. This
might be attributed to di erent sets of attributes between those datasets, e.g.
as IMDB does not contain full-length descriptions of lms and tv shows whereas
TMDB and TVDB do. Interestingly, Films/TVShows with very dissimilar titles
due to di erent representations of non-English titles can be matched using the
KGEs. For example the soviet drama "Defence Counsel Sedov" has the
romanized title "Zashchitnik Sedov" in IMDB, while TMDB has either the translated
"Defence Counsel Sedov" or the cyrillic "Защитник Седов". These entity pairs
are correctly matched in the EAGERAkE variant.</p>
      <p>Looking at the rich datasets it is again evident that EAGERAkE achieves
the best results. Overall it can solve the diverse match tasks including for
multilingual KGs and larger KGs very well with F-Measure values between 96% and
99% in most cases. As before MultiKE with the MLP classi er performs the best</p>
      <sec id="sec-5-1">
        <title>E, RDGCN</title>
      </sec>
      <sec id="sec-5-2">
        <title>E, BootEA</title>
        <sec id="sec-5-2-1">
          <title>A k E, BootEA</title>
          <p>A</p>
        </sec>
        <sec id="sec-5-2-2">
          <title>A k E, MultiKE</title>
        </sec>
      </sec>
      <sec id="sec-5-3">
        <title>E, MultiKE</title>
        <sec id="sec-5-3-1">
          <title>A k E, RDGCN</title>
          <p>out of all graph embedding approaches, which is due to the fact that it explicitly
takes advantage of attribute information of each entity, as opposed to BootEA
and RDGCN.</p>
          <p>Comparing the performances between the datasets we see that on the variants
with richer graph structure (V2) the results are better than on (V1) for the
respective datasets. There is also a di erence when contrasting the di erent
sizes of the datasets. While EAGERAkE with BootEA and MultiKE generally
seem to achieve better results on the larger 100K datasets compared to their
15K counterparts, this is less true for RDGCN.</p>
          <p>
            To properly compare the performance of the approaches across all approaches
we used the statistical analysis presented by Demsar [
            <xref ref-type="bibr" rid="ref7">7</xref>
            ] and the Python
package Autorank [
            <xref ref-type="bibr" rid="ref12">12</xref>
            ], which aims to simplify the use of the proposed methods by
Demsar. The performance measurement for each dataset and classi er are our
paired samples. Given that we have more than two datasets simply using
hypothesis tests for all pairs, would result in a multiple testing problem, which
means the probability of accidentally reporting a signi cant di erence would
be highly increased. We therefore use the procedure recommended by Demsar:
First we test if the average ranks of algorithms are signi cantly di erent using
the Friedman test. If this is the case we perform a Nemenyi test to compare all
classi ers and input combinations.
          </p>
          <p>The null hypothesis of the Friedman test can be rejected (p = 6:572 10 25).
A Nemenyi test is therefore performed and we present the critical distance
diagram in Figure 4. The axis shows the average rank of the input/embedding
combination. Groups that are connected are not signi cantly di erent at the
signi cance level of 0.05, which is internally corrected to ensure that all results
together ful ll this. Approaches that have a higher di erence in average rank
than the critical distance (CD) are signi cantly di erent.</p>
          <p>
            We can see that EAGERAkE with MultiKE signi cantly outperforms all
other variants. This is evidence that the combination of attribute similarities
and embeddings is preferable to using attribute similarities or embeddings on
their own for the task of entity resolution in rich knowledge graphs, even if the
embedding approaches already incorporate attribute information.
We compare our approach to the state-of-the-art ER frameworks Magellan [
            <xref ref-type="bibr" rid="ref16">16</xref>
            ]
and DeepMatcher [
            <xref ref-type="bibr" rid="ref19">19</xref>
            ]. Magellan is an ER framework that allows the use of ML
classi ers for ER. We present the best performing classi ers XGBoost [
            <xref ref-type="bibr" rid="ref5">5</xref>
            ] and
Random Forest (RF). DeepMatcher provides several deep learning solutions for
ER, we employ the hybrid variant which uses a bidirectional recurrent neural
network with a decomposable attention-based attribute summarization module.
To avoid any decrease in performance due to blocking we provide both
frameworks with respective training or test entity mappings directly. Because such
a setup is not possible for the approaches discussed in [
            <xref ref-type="bibr" rid="ref28">28</xref>
            ], which mostly use
resolution strategies based on nearest neighbors, we cannot fairly compare our
approach with theirs and therefore refrain from this comparison here.
          </p>
          <p>We start with the comparison for the shallow datasets. Since both Magellan
and DeepMatcher expect matched schemata we align the attributes by hand
where necessary. We report F-measure (fm), Precison (prec) and Recall (rec)
averaged over the 5 folds. For the comparison with other approaches we use
EAGERAkE with MultiKE and for brevity we will refer to it simply as EAGER.
The results are shown in Table 4. All frameworks perform very well with almost
all F-measure values over 0:95.</p>
          <p>For all three movie datasets Magellan RF outperforms all other approaches
in terms of F-measure.</p>
          <p>5</p>
        </sec>
      </sec>
      <sec id="sec-5-4">
        <title>Magellan RF</title>
      </sec>
      <sec id="sec-5-5">
        <title>Magellan XGBoost</title>
      </sec>
      <sec id="sec-5-6">
        <title>DeepMatcher</title>
      </sec>
      <sec id="sec-5-7">
        <title>EAGER MLP</title>
      </sec>
      <sec id="sec-5-8">
        <title>EAGER RF</title>
        <p>For the rich graph datasets the heterogeneity of the di erent KGs was a
problem for Magellan and DeepMatcher since they both expect perfectly matched
schemata. This was manageable for the smaller datasets, were this can be done
by hand. In order to use Magellan and Deepmatcher on the rich graph datasets
we did the same as for EAGER and concatenated all entity attributes into a
single attribute. We can see that EAGER using MLP outperforms all other
approaches except on D-W (V1) and D-Y (V1) for the 100K sizes, where
DeepMatcher performs best. Magellan is outperformed on all datasets by EAGER
and DeepMatcher.</p>
        <p>The Friedman test shows a signi cant di erence (p = 8:675 10 07). Looking
at the critical distance diagram in Figure 5 we can see that EAGER MLP does
not signi cantly outperform EAGER RF or DeepMatcher, but it is the only
approach that signi cantly outperforms both Magellan approaches. While there
is no signi cant di erence between EAGER MLP and DeepMatcher, EAGER
does not depend on the provision of schema matching.
6</p>
      </sec>
    </sec>
    <sec id="sec-6">
      <title>Conclusion &amp; Future work</title>
      <p>We explored the combination of knowledge graph embeddings and attribute
similarities for entity resolution in knowledge graphs with multiple entity types.
These approaches are included in a new learning-based ER system called
EAGER. We tested our approach on a range of di erent datasets and showed that
using a combination of both graph embeddings and attribute similarities
generally yields the best results compared to just using either one. We showed that
our approach yields competitive results that are on par with or signi cantly
outperform state of the art approaches. The approach is generic and can deal with
several entity types without prior schema matching.</p>
      <p>
        Future work will investigate blocking strategies utilizing both embeddings
and attribute information, as well as smarter attribute combination strategies
(e.g. using property matching[
        <xref ref-type="bibr" rid="ref2">2</xref>
        ]). Unsupervised and active learning in this
context should be explored to alleviate the di culty of obtaining training data.
Acknowledgments. This work was supported by the German Federal Ministry
of Education and Research (BMBF, 01/S18026A-F) by funding the competence
center for Big Data and AI "ScaDS.AI Dresden/Leipzig". Some computations
have been done with resources of Leipzig University Computing Center.
      </p>
    </sec>
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