<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Archiving and Interchange DTD v1.0 20120330//EN" "JATS-archivearticle1.dtd">
<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Can FCA Provide a Framework for AGI?</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Francisco J. Valverde-Albacete</string-name>
          <email>francisco.valverde@urjc.es</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Carmen Peláez-Moreno</string-name>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Inma P. Cabrera</string-name>
          <email>ipcabrera@uma.es</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Pablo Cordero</string-name>
          <email>pcordero@uma.es</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Manuel Ojeda-Aciego</string-name>
          <email>aciego@uma.es</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Depto. Matemática Aplicada, Univ. de Málaga</institution>
          ,
          <addr-line>Málaga</addr-line>
          ,
          <country country="ES">Spain</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Depto. Teoría de Señal y Comunicaciones, Sistemas Telemáticos y Computación, Univ. Rey Juan Carlos</institution>
          ,
          <addr-line>Madrid</addr-line>
          ,
          <country country="ES">Spain</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>Depto. Teoría de Señal y Comunicaciones, Univ. Carlos III de Madrid</institution>
          ,
          <addr-line>Madrid</addr-line>
          ,
          <country country="ES">Spain</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>This paper is an attempt at bridging two strains of research being developed by the authors: a theory of information flows to subserve intelligence and a theory of afordances for the modelling of Embodied, Embedded, Extended and Enacted Computational Intelligence as provided by FCA. We list previous successes, present challenges, and future avenues of research that suggest themselves. One of the inceptors of present-day's state-of-the-art in AI, blames the failure of old-time, symbol-based incarnation of AI on its refusal to take Biological Neural Networks (BNN) as a source of inspiration [1]. They cite three “generations” of NN in Machine Learning (ML) and suggest how each succeeded, once the hurdles of modelling specific behaviour of neural tissue and devising computational techniques to implement them were overcome. In the Ecological Theory of Perception [2] intelligence amounts to performant cognition. At least in one stream of Cognitive Theory, cognition is embodied, embedded, extended and enacted (4E) [3]. These adjectives refer to qualities that the system organism-within-an-environment should have to demonstrate cognition and ultimately intelligence: • embodiment, refers to having a body to behave with, • embedding, to being situated within an enveloping environment, • extension, to the fact that organisms can supplement their bodies through tools to extend their efect onto the environment, and Published in Sergei O. Kuznetsov, Amedeo Napoli, Sebastian Rudolph (Eds.): The 10th International Workshop "What can FCA do for Artificial Intelligence?", FCA4AI 2022, co-located with IJCAI-ECAI 2022, July 23 2022, Vienna, Austria, Proceedings, pp. 35-40. * Corresponding author.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;Formal Concept Analysis</kwd>
        <kwd>Embodied</kwd>
        <kwd>Embedded</kwd>
        <kwd>Extended and Enacted Intelligence</kwd>
        <kwd>Afordances</kwd>
        <kwd>Qualitative Semantics</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>• enaction, to the fact that the interaction with the environment, e.g. carrying out behaviours,
mediates in developing meaning and goals for the organism.</p>
      <p>
        In this paper we speculate about machines attaining (4E) intelligence—as a synonym of (Natural)
General Intelligence—using the techniques and tools stemming from Formal Concept Analysis
(FCA), as the general framework to deal with Galois connections induced by formal contexts [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ].
      </p>
      <p>
        From the description of the phenomenology of cognition and intelligence above, we move
naturally onto the design of 4E intelligence: one way forward is to invoke the Predictive Coding
or Processing hypothesis [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ]. We have elsewhere summarized how this leads to a series of
hypotheses about the forward and backward flows of information in BNN [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ], to wit:
• BNN implement communications at multiple spatial and temporal scales with the goal of
maintaining enaction through the sensory-motor loop closed by the environment. In this
view, rhythms at diferent temporal scales subserve both the information flow along dual
forwards/backwards streams as well as the prediction of the timing of events at diferent
time-scales adapted to environment dynamics [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ].
• BNNs are instances of biological Complex Dynamical Systems (CDS), whose model [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ] is
tuple (, , , , Ω) describing an agent (that defines the “internal” space) embedded
within and environment (defining the “external” space) with explicit dependences on the
tuple of states  = (, ), and implicit dependence on a set of statistical parameters  ,
where we have
      </p>
    </sec>
    <sec id="sec-2">
      <title>a) hidden external states  ∈  ⊂</title>
      <p>, modeling the outer environment,
R, governed by a nonlinear funtion  :  ×  ×  →</p>
    </sec>
    <sec id="sec-3">
      <title>b) sensory states  ∈  ⊂</title>
      <p>R, governed by another nonlinear function  :  ×  ×  →
, capturing the evolution of perception,
c) hidden internal states</p>
      <p>∈  ⊂
 ×  ×  →  capturing its evolution, and
 →  designed to drive the dynamics,
d) (control) actions  ∈  ⊂</p>
      <p>R, governed by another nonlinear function  :  ×  ×</p>
      <p>R, governed by another nonlinear function  :
 ˙ =  (,  ;  ) + 
 ˙ =  (,  ;  ) + 
˙ = (, ;  ) + 
˙ = (, ;  ) + 
(1)
e) Ω is a sample space from which random fluctuations  ∈ R,  ∈ R,  ∈ R,

and</p>
      <p>
        ∈ R are drawn.
• Free-Energy (FE) models are specializations of said CDS, Bayesian models developed to
reconcile the predictive coding hypothesis with neural architectures in a sensory-motor
loop [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ]. A basic FE model is a scale-agnostic model of the behaviour of situated agents
for perception and learning [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ].
• Neural processing is the communication of entropy flows though BNN. However, entropy
being a quantitative property of probability measure values, it is “blind” to any particular
events or “bins” of distributions, so
their information sources to their destinations.
      </p>
      <p>• BNN require topical maps to keep track of the qualities quantified by entropy flows from
For lack of a better name, let’s call the model we envision a 4E Artificial Neural Network (4E-ANN) .
Then these should be machines (embodied) that route entropy—the quantity of information—
lfows between sensors, actuators and the environment (embodied and embedded) and provide
interpretation of these—the quality of information—in the form of connectivity or topic maps,
to subserve their own goals (so as to attain extension and enaction).
2. The Afordances of FCA for a theory of 4E Intelligence:</p>
      <p>
        Quanta and Qualia
2.1. The Formal Qualia in Binary Formal Contexts
Ever since Wille himself cautioned against only reading hierarchical knowledge from FCA,
there have been attempts at “other readings” from the information collected in a formal context,
e.g. [
        <xref ref-type="bibr" rid="ref10 ref11">10, 11</xref>
        ].
      </p>
      <p>
        Recently, we have been calling collectively these three kinds of analyses emanating from a
formal context Formal Context Analysis [
        <xref ref-type="bibr" rid="ref12 ref13 ref14">12, 13, 14</xref>
        ] but we now think about these in terms of
Formal Context Transform (FCT), using an analogy based on Fourier Analysis:
• In the analysis phase of any type of FCT the information contained in a formal context K
is described in terms of the formal qualia (sing. quale), basic abstractions  that capture
some essence of mathematical modelling, e.g. chains, antichains, partitions, etc. endowed
with a partial order ⟨, ≤ ⟩. The sets of formal qualia result in a pair of (possibly dual)
complete lattices join- or meet-embedded within their order.
• In the synthesis phase using the join- and meet-irreducibles of some complete lattice
⟨, ≤ ⟩ we synthesise a context that would return an isomorphic lattice ′ ≡ .
The composition of both steps only allows us to maintain structure up to an isomorphism that
aligns with the restrictions that the formal qualia allow, that is, they provide a focus or lens on
some type of information included in the context, missing others:
• FCA, the analysis in terms of upper and lower bounds of the order imposed by the polars
of the context on the object extents and attribute intents, producing quale dependence or
hierarchy.
• FIA, the analysis in terms of maximal antichains of that order, evincing quale independence
and
• FEA, the analysis in terms of the equivalence relations which are refinements of the
standard congruences on objects and attributes imposed by the polars of the context,
evincing quale undistinguishability.
      </p>
      <p>But whether there might be other types of FCT is still an open issue.
2.2. The Need for Quantification in Modelling AI with FCA
A simplified (no control (), only considers  and  states), linearized, discrete-time form of
(1) can be Z-transformed as:
 +1 =  ·   + 
 =  ·   + 
(2)
learned1.
where the instantaneous transition and observation matrices  and , respectively, are to be
K = ⟨,  , ⟩, describing its instantaneous observation process.</p>
      <p>We know that when the underlying algebra is an idempotent semifield</p>
      <p>
        Considering a set of state and observation dimensions  and , respectively, and by virtue
of the cryptomorphism between matrices with entries in an algebra, bipartite digraphs with

weights in an algebra and relationships with strength in an algebra, we may consider the
formal contexts K = ⟨ ,  , ⟩, describing the instantaneous dynamics of the CDS, and
 these formal contexts
allow the definition of -FCA, that provides the FCA-flavour of analysis in a quantitative
setting [
        <xref ref-type="bibr" rid="ref15">15</xref>
        ]. Indeed, the linear spaces associated with the input and output spaces of  and
 are dually-isomorphic lattices that describe hierarchies of (quantitative) vectors that prove
that standard FCA is the analogue of the Singular Value Decomposition for linear forms over
vector spaces over idempotent semifields [
        <xref ref-type="bibr" rid="ref16">16</xref>
        ].
      </p>
      <p>
        In fact, there are also diferent “conceptualizations” of the spaces associated with a matrix that
resembles the structures needed for FIA and FEA [
        <xref ref-type="bibr" rid="ref17 ref18">17, 18</xref>
        ], and also the concept of “disparity” or
“discord” [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ] can be modelled in the fuzzy setting—a sister theory to -FCA. This is a diferent
quale to those seen above, and a certain sign that more formal qualia can be discovered.
      </p>
      <p>At least all of these (and more) strains of research would need to be fused to be able to
provide instantaneous lattice-like pictures of what (2) represents. Note that, after our argument,
important concepts in the study of CDS, e.g. phase space, evolve in a (constrained) lattice and
therefore trajectories and cycles may take strange forms, unseen so far.
3. Conclusions: Towards a Quanta-and-Qualia Theory of 4E</p>
      <sec id="sec-3-1">
        <title>Intelligence</title>
        <p>
          In summary, we believe the generic FCA framework shows promise to help with modelling 4E
intelligence, e.g. as encapsulated in a model like Friston’s [
          <xref ref-type="bibr" rid="ref8">8</xref>
          ]. But in order to do so, it has to be
extended:
• Qualitatively, by enabling the inference of new formal qualia that cater for a better
foundation of enaction and modelling the information-distinctions efectively carried out
by BNNs. This is the purpose of our eforts towards better understanding FCT [
          <xref ref-type="bibr" rid="ref20">20</xref>
          ].
1Note that this is a qualitatively diferent model to that of (1).
        </p>
        <p>
          • Quantitatively, by enabling such qualitative inferences in the presence of quantitatively
rich data, e.g. as provided by transition and observation matrices with entries in an
information semifield. This is the purpose of our eforts towards understanding information
semifields [
          <xref ref-type="bibr" rid="ref21">21</xref>
          ], their linear-algebraic constructions [
          <xref ref-type="bibr" rid="ref17 ref22">22, 17</xref>
          ], and their relationship with
Galois connections [
          <xref ref-type="bibr" rid="ref18 ref23">23, 18</xref>
          ].
        </p>
        <p>This Quantitative-and-Qualitative, or Quanta-and-Qualia (QaQ) theory of 4E-intelligences
seems a promising point for 4E-NN intelligent machines, whose learning theory we have not
even broached in this paper. This is left for future work.</p>
      </sec>
      <sec id="sec-3-2">
        <title>Acknowledgments</title>
        <p>FVA and CPM were partially funded in the EMERGE project (PID2021-125780NB-I00) by the
Spanish Ministry of Science and Innovations. IPC, PC and MOA were partially supported
by the Spanish Ministry of Science, Innovation, and Universities (MCIU), State Agency of
Research (AEI), Junta de Andalucía (JA), Universidad de Málaga (UMA) and European Regional
Development Fund (FEDER) through the projects PGC2018-095869-B-I00 (MCIU/AEI/FEDER),
TIN2017-89023-P (MCIU/AEI/FEDER), and UMA2018-FEDERJA-001 (JA/UMA/FEDER).</p>
      </sec>
    </sec>
  </body>
  <back>
    <ref-list>
      <ref id="ref1">
        <mixed-citation>
          [1]
          <string-name>
            <surname>T. J</surname>
          </string-name>
          . Sejnowski,
          <article-title>The unreasonable efectiveness of deep learning in artificial intelligence</article-title>
          ,
          <source>Proc Natl Acad Sci USA</source>
          <volume>117</volume>
          (
          <year>2020</year>
          )
          <fpage>30033</fpage>
          -
          <lpage>30038</lpage>
          . doi:
          <volume>10</volume>
          .1073/pnas.1907373117.
        </mixed-citation>
      </ref>
      <ref id="ref2">
        <mixed-citation>
          [2]
          <string-name>
            <given-names>E. J.</given-names>
            <surname>Gibson</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A. D.</given-names>
            <surname>Pick</surname>
          </string-name>
          ,
          <article-title>An Ecological Approach to Perceptual Learning and Development</article-title>
          , Oxford University Press,
          <year>2000</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref3">
        <mixed-citation>
          [3]
          <string-name>
            <given-names>A.</given-names>
            <surname>Newen</surname>
          </string-name>
          , L. de Bruin, S. Gallagher (Eds.),
          <source>The Oxford Handbook of 4E Cognition</source>
          , Oxford University Press, London,
          <year>2018</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref4">
        <mixed-citation>
          [4]
          <string-name>
            <given-names>B.</given-names>
            <surname>Ganter</surname>
          </string-name>
          ,
          <string-name>
            <given-names>R.</given-names>
            <surname>Wille</surname>
          </string-name>
          ,
          <source>Formal Concept Analysis: Mathematical Foundations</source>
          , Springer, Berlin, Heidelberg,
          <year>1999</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref5">
        <mixed-citation>
          [5]
          <string-name>
            <given-names>J.</given-names>
            <surname>Hohwy</surname>
          </string-name>
          ,
          <source>The Predictive Processing Hypothesis, in: The Oxford Handbook of 4E Cognition</source>
          ,
          <string-name>
            <surname>OUP</surname>
          </string-name>
          ,
          <year>2018</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref6">
        <mixed-citation>
          [6]
          <string-name>
            <given-names>F. J.</given-names>
            <surname>Valverde-Albacete</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C.</given-names>
            <surname>Peláez-Moreno</surname>
          </string-name>
          ,
          <article-title>The case for quantifying artificial general intelligence with entropy semifields</article-title>
          , in: E. Pap (Ed.),
          <source>Artificial Intelligence: Theory and Applications</source>
          , Springer Berlin Heidelberg,
          <year>2021</year>
          , pp.
          <fpage>1</fpage>
          -
          <lpage>18</lpage>
          . URL: https://link.springer.com/ chapter/10.1007/978-3-
          <fpage>030</fpage>
          -72711-
          <issue>6</issue>
          _5. doi:
          <volume>10</volume>
          .1007/978-3-
          <fpage>030</fpage>
          -72711-6.
        </mixed-citation>
      </ref>
      <ref id="ref7">
        <mixed-citation>
          [7]
          <string-name>
            <given-names>L. H.</given-names>
            <surname>Arnal</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.-L.</given-names>
            <surname>Giraud</surname>
          </string-name>
          ,
          <article-title>Cortical oscillations and sensory predictions</article-title>
          ,
          <source>Trends in Cognitive Sciences</source>
          <volume>16</volume>
          (
          <year>2012</year>
          )
          <fpage>390</fpage>
          -
          <lpage>398</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref8">
        <mixed-citation>
          [8]
          <string-name>
            <given-names>K. J.</given-names>
            <surname>Friston</surname>
          </string-name>
          ,
          <string-name>
            <given-names>W.</given-names>
            <surname>Wiese</surname>
          </string-name>
          ,
          <string-name>
            <given-names>J. A.</given-names>
            <surname>Hobson</surname>
          </string-name>
          ,
          <article-title>Sentience and the Origins of Consciousness: From Cartesian Duality to Markovian Monism</article-title>
          ,
          <source>Entropy</source>
          <volume>22</volume>
          (
          <year>2020</year>
          )
          <article-title>516</article-title>
          . doi:
          <volume>10</volume>
          .3390/ e22050516.
        </mixed-citation>
      </ref>
      <ref id="ref9">
        <mixed-citation>
          [9]
          <string-name>
            <given-names>R.</given-names>
            <surname>Bogacz</surname>
          </string-name>
          ,
          <article-title>A tutorial on the free-energy framework for modelling perception and learning</article-title>
          ,
          <source>Journal of Mathematical Psychology</source>
          <volume>76</volume>
          (
          <year>2017</year>
          )
          <fpage>198</fpage>
          -
          <lpage>211</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref10">
        <mixed-citation>
          [10]
          <string-name>
            <given-names>I.</given-names>
            <surname>Düntsch</surname>
          </string-name>
          , G. Gediga,
          <article-title>Modal-style operators in qualitative data analysis</article-title>
          ,
          <source>in: Proc. IEEE International Conference on Data Mining, ICDM</source>
          <year>2002</year>
          ,
          <year>2002</year>
          , pp.
          <fpage>155</fpage>
          -
          <lpage>162</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref11">
        <mixed-citation>
          [11]
          <string-name>
            <given-names>D.</given-names>
            <surname>Dubois</surname>
          </string-name>
          ,
          <string-name>
            <given-names>H.</given-names>
            <surname>Prade</surname>
          </string-name>
          ,
          <article-title>Possibility theory and formal concept analysis: Characterizing independent sub-contexts</article-title>
          ,
          <source>Fuzzy Sets and Systems</source>
          <volume>196</volume>
          (
          <year>2012</year>
          )
          <fpage>4</fpage>
          -
          <lpage>16</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref12">
        <mixed-citation>
          [12]
          <string-name>
            <given-names>F. J.</given-names>
            <surname>Valverde-Albacete</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C.</given-names>
            <surname>Peláez-Moreno</surname>
          </string-name>
          ,
          <string-name>
            <given-names>I. P.</given-names>
            <surname>Cabrera</surname>
          </string-name>
          ,
          <string-name>
            <given-names>P.</given-names>
            <surname>Cordero</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Ojeda-Aciego</surname>
          </string-name>
          ,
          <article-title>Formal independence analysis</article-title>
          ,
          <source>Communications in Computer and Information Science</source>
          <volume>853</volume>
          (
          <year>2018</year>
          )
          <fpage>596</fpage>
          -
          <lpage>608</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref13">
        <mixed-citation>
          [13]
          <string-name>
            <given-names>F. J.</given-names>
            <surname>Valverde-Albacete</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C.</given-names>
            <surname>Peláez-Moreno</surname>
          </string-name>
          ,
          <string-name>
            <given-names>I. P.</given-names>
            <surname>Cabrera</surname>
          </string-name>
          ,
          <string-name>
            <given-names>P.</given-names>
            <surname>Cordero</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Ojeda-Aciego</surname>
          </string-name>
          ,
          <article-title>A Data Analysis Application of Formal Independence Analysis</article-title>
          ,
          <source>in: Concept Lattices and their Applications (CLA'18)</source>
          ,
          <year>2018</year>
          , pp.
          <fpage>1</fpage>
          -
          <lpage>12</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref14">
        <mixed-citation>
          [14]
          <string-name>
            <given-names>F. J.</given-names>
            <surname>Valverde-Albacete</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C.</given-names>
            <surname>Peláez-Moreno</surname>
          </string-name>
          ,
          <string-name>
            <given-names>P.</given-names>
            <surname>Cordero</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Ojeda-Aciego</surname>
          </string-name>
          ,
          <article-title>Formal equivalence analysis</article-title>
          ,
          <source>in: Proc. Conf. Internat. Fuzzy Syst. Assoc. and European Soc. Fuzzy Logic and Technol</source>
          .
          <source>(EUSFLAT</source>
          <year>2019</year>
          ), Atlantis Press,
          <year>2019</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref15">
        <mixed-citation>
          [15]
          <string-name>
            <given-names>F. J.</given-names>
            <surname>Valverde-Albacete</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C.</given-names>
            <surname>Peláez-Moreno</surname>
          </string-name>
          ,
          <article-title>Extending conceptualisation modes for generalised Formal Concept Analysis</article-title>
          ,
          <source>Information Sciences 181</source>
          (
          <year>2011</year>
          )
          <fpage>1888</fpage>
          -
          <lpage>1909</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref16">
        <mixed-citation>
          [16]
          <string-name>
            <given-names>F. J.</given-names>
            <surname>Valverde-Albacete</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C.</given-names>
            <surname>Peláez-Moreno</surname>
          </string-name>
          ,
          <article-title>The Linear Algebra in Extended Formal Concept Analysis Over Idempotent Semifields</article-title>
          , in: K.
          <string-name>
            <surname>Bertet</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          <string-name>
            <surname>Borchmann</surname>
            ,
            <given-names>P.</given-names>
          </string-name>
          <string-name>
            <surname>Cellier</surname>
          </string-name>
          , S. Ferré (Eds.),
          <source>Formal Concept Analysis</source>
          , Springer Berlin Heidelberg, Rennes,
          <year>2017</year>
          , pp.
          <fpage>211</fpage>
          -
          <lpage>227</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref17">
        <mixed-citation>
          [17]
          <string-name>
            <given-names>F. J.</given-names>
            <surname>Valverde-Albacete</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C.</given-names>
            <surname>Peláez-Moreno</surname>
          </string-name>
          ,
          <article-title>Four-fold formal concept analysis based on complete idempotent semifields</article-title>
          ,
          <source>Mathematics MDPI 9</source>
          (
          <year>2021</year>
          )
          <article-title>173</article-title>
          . URL: https://www.mdpi. com/2227-7390/9/2/173. doi:
          <volume>10</volume>
          .3390/math9020173.
        </mixed-citation>
      </ref>
      <ref id="ref18">
        <mixed-citation>
          [18]
          <string-name>
            <given-names>I.</given-names>
            <surname>Cabrera</surname>
          </string-name>
          ,
          <string-name>
            <given-names>P.</given-names>
            <surname>Cordero</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Ojeda-Aciego</surname>
          </string-name>
          ,
          <article-title>On fuzzy relations, functional relations, and adjunctions</article-title>
          ,
          <source>in: Proc. of Foundations of Computational Intelligence</source>
          , FOCI,
          <year>2016</year>
          . doi:
          <volume>10</volume>
          . 1109/SSCI.
          <year>2016</year>
          .
          <volume>7850149</volume>
          .
        </mixed-citation>
      </ref>
      <ref id="ref19">
        <mixed-citation>
          [19]
          <string-name>
            <given-names>N.</given-names>
            <surname>Madrid</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Ojeda-Aciego</surname>
          </string-name>
          ,
          <article-title>Residuated structures via the f-index of inclusion</article-title>
          ,
          <source>in: Computational and Mathematical Methods in Science and Engineering</source>
          ,
          <year>2021</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref20">
        <mixed-citation>
          [20]
          <string-name>
            <given-names>F. J.</given-names>
            <surname>Valverde-Albacete</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C.</given-names>
            <surname>Peláez-Moreno</surname>
          </string-name>
          ,
          <string-name>
            <given-names>P.</given-names>
            <surname>Cordero</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Ojeda-Aciego</surname>
          </string-name>
          ,
          <article-title>Formal context transforms</article-title>
          , In preparation (
          <year>2022</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref21">
        <mixed-citation>
          [21]
          <string-name>
            <given-names>J. F.</given-names>
            <surname>Valverde-Albacete</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C.</given-names>
            <surname>Peláez-Moreno</surname>
          </string-name>
          ,
          <source>The Rényi Entropies Operate in Positive Semifields, Entropy</source>
          <volume>21</volume>
          (
          <year>2019</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref22">
        <mixed-citation>
          [22]
          <string-name>
            <given-names>F. J. Valverde</given-names>
            <surname>Albacete</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C.</given-names>
            <surname>Peláez-Moreno</surname>
          </string-name>
          ,
          <article-title>The Singular Valued Decomposition over completed idempotent semifields</article-title>
          ,
          <source>Mathematics MDPI</source>
          (
          <year>2020</year>
          )
          <fpage>1</fpage>
          -
          <lpage>39</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref23">
        <mixed-citation>
          [23]
          <string-name>
            <given-names>F. J.</given-names>
            <surname>Valverde-Albacete</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C.</given-names>
            <surname>Peláez-Moreno</surname>
          </string-name>
          ,
          <article-title>K-formal concept analysis as linear algebra over idempotent semifields</article-title>
          ,
          <source>Information Sciences 467</source>
          (
          <year>2018</year>
          )
          <fpage>579</fpage>
          -
          <lpage>603</lpage>
          .
        </mixed-citation>
      </ref>
    </ref-list>
  </back>
</article>