=Paper= {{Paper |id=Vol-3174/paper3 |storemode=property |title=Solving Morphological Analogies Through Generation |pdfUrl=https://ceur-ws.org/Vol-3174/paper3.pdf |volume=Vol-3174 |authors=Kevin Chan,Shane P. Kaszefski-Yaschuk,Camille Saran,Esteban Marquer,Miguel Couceiro |dblpUrl=https://dblp.org/rec/conf/ijcai/ChanKSMC22 }} ==Solving Morphological Analogies Through Generation== https://ceur-ws.org/Vol-3174/paper3.pdf
Solving Morphological Analogies Through Generation
Kevin Chan1,† , Shane P. Kaszefski-Yaschuk1,† , Camille Saran1,† , Esteban Marquer1 and
Miguel Couceiro1,*
1
    Université de Lorraine, CNRS, LORIA, F-54000, France


                                         Abstract
                                         This contribution is a first attempt at solving morphological analogies through generation, instead
                                         of relying on retrieval approaches. Our preliminary experiments show promising results for some
                                         languages and reveal the feasibility of the approach in generating solutions of analogical equations in
                                         the morphology setting.

                                         Keywords
                                         Morphological analogy, Analogy solving, Representation learning, Word generation




1. Introduction
Analogical proportions are understood as statements of the form “𝐴 is to 𝐵 as 𝐶 is to 𝐷”
denoted 𝐴 : 𝐵 :: 𝐶 : 𝐷, and they are the basis of analogical inference. Analogical inference is
a remarkable capability of human reasoning, and that has been used to solve hard reasoning
tasks. To some extent, it can be thought of as transferring knowledge from a source domain
to a different, but somewhat similar, target domain by relying simultaneously on similarities
and dissimilarities. Analogy based reasoning (AR) is closely related to case-based reasoning
and has gained increasing interest from the artificial intelligence (AI) community, and has
shown its potential in multiple machine learning (ML) tasks such as classification, decision
making and recommendation with competitive results [1, 2, 3, 4]. Furthermore, analogical
inference can support data augmentation through analogical extension and extrapolation for
model learning, especially in environments with few labeled examples [5]. Also, it has been
successfully applied to several classical NLP tasks such as machine translation [6], several
semantic and morphological tasks [7, 8, 9], as well as (visual) question answering and solving
puzzles and scholastic aptitude tests [10, 11].
   There are two basic tasks associated with AR. The first is analogy detection that corresponds
to the task of deciding whether a quadruple 𝐴, 𝐵, 𝐶, 𝐷 constitutes a valid analogical proportion.
This task asks for a common theoretical framework. However, the notion of analogy is not

IARML@IJCAI-ECAI’2022: Workshop on the Interactions between Analogical Reasoning and Machine Learning, at
IJCAI-ECAI’2022, July, 2022, Vienna, Austria
*
  Corresponding author.
†
  Equal contribution.
$ kevin.chan3@etu.univ-lorraine.fr (K. Chan); shane-peter.kaszefski-yaschuk5@etu.univ-lorraine.fr
(S. P. Kaszefski-Yaschuk); camille.saran5@etu.univ-lorraine.fr (C. Saran); esteban.marquer@loria.fr (E. Marquer);
miguel.couceiro@loria.fr (M. Couceiro)
 0000-0003-2315-7732 (E. Marquer); 0000-0003-2316-7623 (M. Couceiro)
                                       © 2022 Copyright for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
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    Workshop
    Proceedings
                  http://ceur-ws.org
                  ISSN 1613-0073
                                       CEUR Workshop Proceedings (CEUR-WS.org)




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Kevin Chan et al.                                     IARML@IJCAI-ECAI’22 Workshop Proceedings


consensual, and there have been several efforts that follow different axiomatic and logical
approaches [12, 13]. For instance, [14] introduces the following 4 postulates in the linguistic
context as a guideline for formal models of analogical proportions: symmetry (if 𝐴 : 𝐵 :: 𝐶 : 𝐷,
then 𝐶 : 𝐷 :: 𝐴 : 𝐵), central permutation (if 𝐴 : 𝐵 :: 𝐶 : 𝐷, then 𝐴 : 𝐶 :: 𝐵 : 𝐷), strong
inner reflexivity (if 𝐴 : 𝐴 :: 𝐶 : 𝐷, then 𝐷 = 𝐶), and strong reflexivity (if 𝐴 : 𝐵 :: 𝐴 : 𝐷, then
𝐷 = 𝐵). Such postulates appear reasonable in the word domain, but they can be criticized in
other application domains [15, 16].
   The second basic task is analogy solving that refers to the task of extrapolating or generating,
for a given triple 𝐴, 𝐵, 𝐶 the value 𝑋 such that 𝐴 : 𝐵 :: 𝐶 : 𝑋 is a valid analogy. One approach
to tackling this task is by retrieval and adaptation, i.e., defining an 𝑋 from a pool of retrieved
candidate solutions to be suitably adapted. In fact, analogy solving is somewhat related to
case-based reasoning (CBR) [17] where, given a set 𝑃 of problems, a set 𝑆 of solutions and a set
𝒞 of cases (𝑥, 𝑦) ∈ 𝑃 × 𝑆, the CBR task is to find a solution 𝑦𝑡 to a given target problem 𝑥𝑡 .
CBR basically consists in (1) selecting 𝑘 source cases in the case base according to some criteria
related to the target problem (retrieval step), and (2) reusing the 𝑘 retrieved cases for proposing
a target solution (adaptation step). Despite being a reasonable approach in controlled settings,
it suffers from several drawbacks: it requires a suitable choice of examples and is intrinsically
limited by case based approaches, that prevent creative inference and innovation.
   More recent approaches to analogy solving take advantage of recent deep neural network
frameworks that rely on vector representations and on the structure of the underlying multidi-
mensional space. Essentially, analogical proportions are formalized in terms of the parallelogram
rule by which four vectors 𝑒𝐴 , 𝑒𝐵 , 𝑒𝐶 , and 𝑒𝐷 (representing four elements 𝐴, 𝐵, 𝐶, and 𝐷)
are in analogical proportion if 𝑒𝐷 − 𝑒𝐶 = 𝑒𝐵 − 𝑒𝐴 . Such an arithmetic view of analogical
proportions has been used since the first works on analogy [18], and it was the key element
in the methodology employed by earlier neural-based approaches [19, 20]. In the absence of
a decoder, the authors implicitly generate a representation 𝑒𝑋 and then retrieve the closest
candidate 𝐷 from the vocabulary to solve the analogical equation 𝐴 : 𝐵 :: 𝐶 : 𝑋 (see brief
discussion of Subsection 2.2). However, Chen et al. [21] argue that the latter two methods
significantly differ from human performance.
   In the case of sentence analogies (i.e., where 𝐴, 𝐵, 𝐶 are sentences), [22] overcomes this issue
by training a decoder that is then used to decode 𝑒𝑋 . In this paper, we employ a similar approach
in the setting of word analogies. More precisely, following the tracks of [23, 24, 25], we address
morphological issues on words and tackle the problem of solving morphological analogies.
Inspired by the work of [22] to solving sentence analogies, the novelty in our contribution is
to make use of autoencoders to solving morphological analogies on words. More precisely,
the main contributions of this paper are as follows: (i) we propose a model to generate words
at character level from word embeddings with high reconstruction performance, and (ii) we
achieve encouraging results to solving morphological analogies by generation, thus indicating
the feasibility of the approach. Nonetheless, this constitutes ongoing research that requires
further investigations.
   The paper is organized as follows. We first briefly survey previous work on both main tasks
dealing with morphological analogies in Section 2. We then describe the key components of the
deep learning architecture as well as the analogy solving procedure we use in Section 3. The
empirical setting setting is then presented in Section 4 where we also discuss the experimental




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Kevin Chan et al.                                    IARML@IJCAI-ECAI’22 Workshop Proceedings


results. We conclude with a general overview of this contribution in Section 5 and propose
further directions of future research.


2. Related Approaches
In this paper, we focus on morphological analogies, i.e., analogies on words 𝐴, 𝐵, 𝐶, and
𝐷 that capture morphological transformations of words (e.g., conjugation or declension). In
this section we introduce key approaches of analogy detection and solving in morphology.
The main trend follows the seminal work of [26] by exploiting the postulates of analogical
proportions mentioned in introduction, but some approaches including ours take a slightly
different approach. As deep learning approaches to morphological analogies are strongly related
to approaches on semantic word analogies, the latter will also be discussed here.

2.1. Analogy Detection
As mentioned above, the analogy detection task corresponds to classifying quadruples
𝐴, 𝐵, 𝐶, 𝐷 into valid or invalid analogies. The tools in [27] detect morphological analogies
using the number of characters occurrences and the length of the longest common subword.
Their approach is designed to generate analogical grids, i.e., matrices of transformations of
various words, similar to paradigm tables in linguistics [7]. A data-driven alternative was imple-
mented by [8] for semantic word analogies. Using a dataset of semantic analogies, they learn a
neural network to classify quadruples 𝐴, 𝐵, 𝐶, 𝐷 into valid or invalid analogies, using their
embedding 𝑒𝐴 , 𝑒𝐵 , 𝑒𝐶 , and 𝑒𝐷 . This approach was applied to morphological analogies in [24]
by replacing the GloVe [28] semantic embeddings used by Lim et al. with a morphology-oriented
word embedding model.

2.2. Analogy Solving
Approaches to analogy solving usually generate the fourth element to solve the analogy, but
it is also possible to leverage a list of candidates and retrieve the most fitting fourth term to
solve the analogy. In Subsubsection 2.2.2 we describe key approaches using the former method
to solve morphological analogies, and similarly in Subsubsection 2.2.1 for the latter method.
Many approaches in embedding spaces use the latter method because generation from an
embedding space can be challenging, and we describe some in Subsubsection 2.2.1. However,
such retrieval approaches are limited to the available vocabulary and are unable to perform
analogical innovation, despite it being a key mechanism in the evolution of languages [29, 30].

2.2.1. Retrieval
Analogy solving on word embeddings has been around since early works on La-
tent Semantic Analysis [31] and word embeddings [20, 23], in which examples like
𝑘𝑖𝑛𝑔 − 𝑚𝑎𝑛 + 𝑤𝑜𝑚𝑎𝑛 = 𝑞𝑢𝑒𝑒𝑛 have been used do demonstrate the ability to encode
semantic features in the word representation. These examples can be formulated as analogical
equations 𝑚𝑎𝑛 : 𝑤𝑜𝑚𝑎𝑛 :: 𝑘𝑖𝑛𝑔 : 𝑋, for which the solution is retrieved among a vocabulary




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Kevin Chan et al.                                                   IARML@IJCAI-ECAI’22 Workshop Proceedings


of candidate words. In [23], the authors use morphological1 analogies to demonstrate that
some word embedding models encode a degree of morphological information. Two of the most
used methods for solving analogies in embedding spaces by retrieval are 3CosAdd [20] and
3CosMul [32]. In 3CosAdd, the solution 𝑋 is retrieved from the vocabulary by minimizing
the cosine distance 𝑐𝑜𝑠(𝑒𝑤𝑜𝑟𝑑 , 𝑒𝑋 ), with 𝑒𝑋 = 𝑒𝐶 − 𝑒𝐴 + 𝑒𝐵 and 𝑒𝐴 , 𝑒𝐵 , 𝑒𝐶 , and 𝑒𝑋 the
embeddings of 𝐴, 𝐵, 𝐶, and 𝑋. 3CosMul follows a similar intuition but we refer the reader
to [32] for a detailed description. However, the quality of the solution produced by the methods
described above have been criticized by [19] for being far from human performance in some
cases. Nonetheless, frameworks based on analogy datasets like those mentioned in [8] appear
to bridge this gap in performance. By replacing the arbitrary formula by a learned estimator,
Lim et al. significantly improved performance on solving semantic word analogies. This latter
approach was adapted to morphological word analogies in [25] and outperforms the generative
methods described in Subsubsection 2.2.2. Those two approaches rely on the postulates of
analogical proportions, and achieve high analogy solving performance.
   While the approach by Marquer et al. has state of the art performance on solving analogical
equations in morphology, it suffers from the limitations of retrieval approaches: the solutions
are retrieved from a de facto finite vocabulary and analogical innovation is impossible. By
using a generative deep learning model, the present work aims to maintain state of the art
performance while solving the limitation of retrieval approaches.

2.2.2. Generation
In [33], the author uses the postulates of [26] to address multiple characteristics of words,
such as their length, the occurrence of letters and of patterns. Based on these features, Lepage
proposes an algorithm to solve analogies between character strings. Following the results of
[34] about closed form solutions, the Alea algorithm [6] proposes a Monte-Carlo estimation
of the solutions of an analogical equation by sampling among multiple sub-transformations.
Those sub-transformations are obtained by considering the words as bags of characters and
generating permutations of characters that are present in 𝐵 but not in 𝐴 on one side, and
characters of 𝐶 on the other. Intuitively, if we consider 𝑏𝑎𝑔(𝐴) the bag of characters in 𝐴,
Alea considers 𝑏𝑎𝑔(𝐷) = (𝑏𝑎𝑔(𝐵) − 𝑏𝑎𝑔(𝐴)) + 𝑏𝑎𝑔(𝐶) and thus 𝐷 is a permutation of the
characters of 𝑏𝑎𝑔(𝐷). Recently, a more empirical approach was proposed by [9], which does not
rely on the axioms of analogical proportions. The generation model proposed by the authors
considers some transformation 𝑓 such that 𝐵 = 𝑓 (𝐴) and 𝑓 (𝐶) is computable. The simplest
transformation 𝑓 is usually the one human use to solve analogies [9], and is found by minimizing
the Kolmogorov complexity of 𝑓 . This complexity is estimated by first expressing 𝑓 using a
language of operations (insertion, deletion, etc.), and computing the length of the resulting
program. Unlike Alea, Kolmo is able to handle mechanisms like reduplication (repeating part of
a word).
   Recently, [22] proposed a generation framework to solving sentence analogies. They use an
autoencoder model (named ConRNN) trained to reconstruct sentences, and perform simple
1
    In [23] the authors refer to morphological transformations as syntactic transformations, because they refer to the
    syntactic role of the word (e.g., past participle) and not the arrangement of its morphemes (e.g., the addition of the
    suffix “-ed”).




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Figure 1: Character-based word auto encoder and vector arithmetic to solve analogies


arithmetic operations on the embedding space to solve analogies. Once the analogy between
embeddings is solved, the decoder part of ConRNN is used to generate the solution from the
predicted embedding. Their model is a sequence-to-sequence model composed of 2 elements.
First, a sentence (as a sequence of words) is used as input to an encoder RNN, and the last hidden
state of the RNN is used as the sentence embedding. The latter is then fed to a decoder RNN
that tries to predict the words of the input sentence. The use of a generative model achieves
significantly better results than previous retrieval approaches on the same embedding space.
The current work aims to extend the one of [25] by replacing the retrieval by the generation of
the solution of morphological analogical equations. To do so, it is necessary to generate words
at the character level from fixed-size embeddings, however in the literature there is to our best
knowledge no approach proposed to tackle this specific issue. Inspired by the success of [22],
we propose a character-level autoencoder for words and display its performance in solving
morphological analogies.


3. Our Approach
In this section we present the approach we use, illustrated in Figure 1. The architecture for
our model is a character-level sequence-to-sequence autoencoder model, based on the model




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Kevin Chan et al.                                    IARML@IJCAI-ECAI’22 Workshop Proceedings


described in [35]. In order to properly decode the final vector solution, the model is trained to
encode words and then decode the resulting vector back into the same word. Each character
in a word 𝑤 is encoded into a one-hot vector and is then fed into the encoder, which uses
a Bidirectional Long Short Term Memory (BiLSTM) layer. This layer outputs four vectors:
the last hidden state ℎ𝑓 and cell state 𝑐𝑓 in the forward direction, and similarly ℎ𝑏 and 𝑐𝑏
for the backward direction. The concatenation of these vectors 𝑒𝑤 = concat(ℎ𝑓 , ℎ𝑏 , 𝑐𝑓 , 𝑐𝑏 ) is
the embedding of the word. The decoder is a regular LSTM layer, followed by a dense layer
with softmax activation. The input for the first step of the decoder is the above-mentioned
embedding, split into two states ℎ = concat(ℎ𝑓 , ℎ𝑏 ) and 𝑐 = concat(𝑐𝑓 , 𝑐𝑏 ). During training,
we use teacher forcing: (i) the characters of the word 𝑤 to predict are used as input, with an
added beginning-of-word (BOW) character at the begining; (ii) the prediction targets are the
characters of 𝑤, but ahead by one time-step and with an end-of-word (EOW) character at the
end.
   To compute the solution of an analogy 𝐴 : 𝐵 :: 𝐶 : 𝑋, the embeddings 𝑒𝐴 , 𝑒𝐵 , and 𝑒𝐶 are
computed by the encoder and used to compute 𝑒𝑋 = 𝑒𝐵 − 𝑒𝐴 + 𝑒𝐶 . Then, 𝑒𝑋 is decoded into
a word 𝑋 by the decoder. Beginning with the BOW character, at each time-step the sampled
character with the highest probability of occurrence is added to the word until either the EOW
character is predicted or the length of the word is the same as the longest word in the dataset.


4. Experiments
In this section we present our experimental setup. First, the dataset we use is described in
Subsection 4.1. We then report the performance of our model in the autoencoder setting in
Subsection 4.2. The analogy solving performance of our approach is compared with baselines
in Subsection 4.3. Finally, we discuss the overall performance of the model in Subsection 4.4.

4.1. Datasets
For our experiments, we used the analogies from 8 languages available in the Siganalogies
dataset [36]: Arabic, English, French, German, Hungarian, Portuguese, Russian, and Spanish
extracted from the high resource languages of Sigmorphon2019 [37]. These languages were
chosen such that, in later stages of the work, the authors have enough linguistic knowledge
to interpret the model outputs. In order to obtain train and test sets, non-overlaping random
subsets of analogies from the entire Sigmorphon dataset for a given language are taken, to
ensure that no analogy is seen in both the train and test sets.
   The Siganalogies dataset also provides a method for data augmentation via permutating
the four words in a given analogy. These permutations are obtained using the symmetry and
central permutation postulates of analogy. From a base form 𝐴 : 𝐵 :: 𝐶 : 𝐷, we generate 7
permutations:

    • 𝐴 : 𝐶 :: 𝐵 : 𝐷;
    • 𝐷 : 𝐵 :: 𝐶 : 𝐴;
    • 𝐶 : 𝐴 :: 𝐷 : 𝐵;
    • 𝐶 : 𝐷 :: 𝐴 : 𝐵;




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Table 1
Autoencoder accuracy at the word level for 8 languages, trained for 100 epochs on 40,000 random words.

                                      Language      Accuracy (%)
                                       Arabic          99.99
                                      English          99.98
                                       French          99.99
                                      German           99.98
                                     Hungarian         99.97
                                     Portuguese        99.99
                                      Russian          99.96
                                      Spanish          99.98


    • 𝐵 : 𝐴 :: 𝐷 : 𝐶;
    • 𝐷 : 𝐶 :: 𝐵 : 𝐴;
    • 𝐵 : 𝐷 :: 𝐴 : 𝐶.

In Siganalogies, the base forms 𝐴 : 𝐵 :: 𝐶 : 𝐷 are such that 𝐵 is an inflected form of 𝐴 and 𝐷
is inflected from 𝐶. In addition to that, base forms 𝐴 : 𝐴 :: 𝐵 : 𝐵 derived from the identity
postulate (𝐴 : 𝐴 :: 𝐵 : 𝐵 is true for all 𝐴 and 𝐵) are present. An example of analogy in English
is dog : dogs :: cat : cats, another in French is revérifier : revérifiasse :: tormenter : tormentasse,
and in German there is Donor : Donor :: Herstellungsverfahren : Herstellungsverfahren (identity,
but also accusative singular declension of the noun).

4.2. Autoencoder performance
As shown in Table 1, our autoencoder achieves very high accuracy in decoding vectors back
into words, meaning that any wrong solutions are a result of the operations performed on
the analogy rather than the decoding process. In our experiments, the model encodes the
words as 128-dimensional vectors and there is a 0.1 dropout on the decoder LSTM layer. The
loss function used is categorical cross-entropy, since a probability for the likelihood of each
character appearing is required at each time-step. An 80/20 train/validation split is used, and the
validation loss was the metric used for the early stopping. If the early stopping is not triggered,
the model is trained for 100 epochs.

4.3. Analogy solving performance
Two metrics are used to determine the performance of our model. The first one is a variation
of Levenshtein distance, which calculates the minimum number of edits required to change
one sequence into another using insertions, deletions, and substitutions. In order to display
how close the decoded analogy solutions are to the expected analogy solutions, the Levenshtein
distance 𝐿 was normalized using the length of the manipulated words into a percentage 𝐿𝑝 like
so:
                                                    𝐿(𝑒𝑥𝑝𝑒𝑐𝑡𝑒𝑑, 𝑑𝑒𝑐𝑜𝑑𝑒𝑑)
                𝐿𝑝 (𝑒𝑥𝑝𝑒𝑐𝑡𝑒𝑑, 𝑑𝑒𝑐𝑜𝑑𝑒𝑑) = 1 −
                                                max (𝑙𝑒𝑛𝑒𝑥𝑝𝑒𝑐𝑡𝑒𝑑 , 𝑙𝑒𝑛𝑑𝑒𝑐𝑜𝑑𝑒𝑑 )




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Kevin Chan et al.                                             IARML@IJCAI-ECAI’22 Workshop Proceedings


Table 2
Results for 8 languages for 10,000 base analogies and all of their permutations (80,000 analogies in total).
We report 𝐿𝑝 in % and the accuracy (Acc.) in %. Our autoencoder was trained for 100 epochs on 40,000
random words per language. Baselines Alea [6] and Kolmo [9] were tested in the same setting. The
accuracy of the retrieval model ANNr [25] is reported as mean ± standard deviation for 10 random
initialization, but note that these results are not completely comparable with our approach as they were
obtained in a closed setting.
                     Language      Score     Ours     Alea      Kolmo       ANNr
                                    𝐿𝑝      54.51     23.72      45.31        –
                       Arabic
                                    Acc.    12.50      2.56       3.81   71.80 ± 2.51
                                    𝐿𝑝      91.58     88.34      86.75        –
                      English
                                    Acc.    59.80     59.65      46.93   94.40 ± 0.67
                                    𝐿𝑝      86.43     80.07      89.32        –
                       French
                                    Acc.    51.30     57.64      54.49   91.84 ± 0.83
                                    𝐿𝑝      89.39     82.76      87.47        –
                      German
                                    Acc.    52.80     50.84      48.97   76.95 ± 1.15
                                    𝐿𝑝      80.32     60.72      75.47        –
                     Hungarian
                                    Acc.    25.50     27.80      23.48   80.42 ± 1.30
                                    𝐿𝑝      94.38     87.97      93.47        –
                    Portuguese
                                    Acc.    74.00     80.06      71.28   89.30 ± 2.38
                                    𝐿𝑝      82.29     63.52      82.78        –
                      Russian
                                    Acc.    33.80     37.15      33.44   72.65 ± 1.96
                                    𝐿𝑝      89.39     79.49      88.56        –
                      Spanish
                                    Acc.    60.09     65.02      58.59   93.01 ± 2.38


The resulting percentage measures the rate of correctly decoded characters per word - when it
is 1 (or 100%), then the decoded solution matches the expected solution perfectly. The second
metric, accuracy, was calculated by dividing the number of correctly decoded analogies by
the total number of analogies for each language. We report the results of decoding a test set
of 10,000 base analogies and their permutations in Table 2. We compare our approach with
Alea [6] and Kolmo [9] described in Subsubsection 2.2.2. We also report the retrieval accuracy
of ANNr [25], however as the model is a retrieval approach it is not directly comparable to our
model and other baselines. Instead, it indicates the performance one can reach when bypassing
the issue of generation. Our model reaches comparable performance to the generation baselines
in terms of 𝐿𝑝 for all languages, and comparable performance in terms of accuracy for half of
the languages.

4.4. Discussion
The performance on Arabic of all generation models is very low, while the retrieval model does
not appear to suffer from the same effect. Further analysis of the data reveals that the character
encoding used for Arabic decomposes each character into multiple encoded characters, resulting




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Kevin Chan et al.                                   IARML@IJCAI-ECAI’22 Workshop Proceedings


in longer and more complex sequences of characters than expected. We suppose this makes
generation harder and is the cause of this low performance.
   There is a significant difference in the performance of the model depending on which permu-
tations are used. Due to the high accuracy of the decoder and the nature of the parallelogram
rule, the model performs very well on analogies where the solution 𝐷 is the same as another
element in the analogical equation. Permutations of this form include strong reflexivity, strong
inner reflexivity, and identity.
   As Table 2 shows, the raw accuracy is often lower than the baselines Alea and Kolmo, but the
Levenshtein percentage is often on par or higher. This suggests that more individual characters
are correctly decoded with our model on average when compared to the baselines, but that it
does not decode entire words with 100% accuracy as often. This is to be expected as the model
is not trained to solve analogies, but rather is trained to properly decode words after vector
arithmetic is performed on the encoded vectors.
   When applied to the encoded vectors, the parallelogram rule is highly accurate with regular
morphology and with certain permutations, but it often struggles when the morphology is
more irregular. Since the model decodes individual words with high accuracy, the problem lies
with the operations performed on the three vectors in an analogical equation after encoding.
Given the model’s current performance without explicitly encoding any morphological features
or features of analogical equations when training, we expect that better performance can be
obtained if these features are included in future iterations of the trained autoencoder.


5. Conclusion and Perspectives
In this paper we proposed an autoencoder framework to solving morphological analogies by
generating solutions. This partially addresses the limitations of previous works relying on
case based approaches that prevent creative inference and innovation. Our adaptation to the
morphology setting was illustrated in several languages with promising results, and that reveal
new potential directions for future work.
   However, this is a preliminary proposal that will profit from further training and the combi-
nation with state of the art retrieval approaches such as ANNr from [25]. Moreover, we will
also explore its tranferability potential and its generalization across multiple modalities and
data contexts.


Acknowledgments
This research work was partially supported by TAILOR, a project funded by EU Horizon 2020
research and innovation program under GA No 952215, and the Inria Project Lab “Hybrid
Approaches for Interpretable AI” (HyAIAI).


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