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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>Workshop on Advances in Argumentation in Artificial Intelligence, September</journal-title>
      </journal-title-group>
    </journal-meta>
    <article-meta>
      <title-group>
        <article-title>Conditionals and Temporal Conditionals for Gradual Argumentation</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Mario Alviano</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Laura Giordano</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Daniele Theseider Dupré</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>DEMACS, University of Calabria</institution>
          ,
          <addr-line>Via Bucci 30/B, 87036 Rende (CS)</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>DISIT, University of Piemonte Orientale</institution>
          ,
          <addr-line>Viale Michel 11, 15121 Alessandria</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2025</year>
      </pub-date>
      <volume>13</volume>
      <issue>2025</issue>
      <fpage>0000</fpage>
      <lpage>0002</lpage>
      <abstract>
        <p>In this paper we develop a preferential interpretation of gradual argumentation and propose an approach for temporal conditional reasoning about argumentation graphs. The approach exploits a two-valued temporal conditional logic with typicality, combining a preferential logic with Linear Time Temporal Logic (LTL). It introduces a dynamic dimension to conditional reasoning in gradual argumentation, enabling the verification of conditional properties across time, such as trends in the evolution of argument strength.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;Preferential and Conditional reasoning</kwd>
        <kwd>Argumentation</kwd>
        <kwd>Temporal Reasoning</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>1. Conceptual simplification: By moving from a many-valued to a two-valued framework, we retain
expressive power while simplifying the formal semantics and reasoning mechanisms.
2. Temporal extension: We introduce a dynamic dimension to conditional reasoning in gradual
argumentation, enabling the verification of conditional properties across time, such as trends in
the evolution of argument strength.</p>
      <p>The proposed logic can be used to analyze time-dependent properties of argumentation graphs, including
iterative updates of strength functions, and is also applicable to weighted knowledge bases and neural
networks interpreted as weighted argumentation frameworks. This opens up new opportunities for
explainability, temporal verification, and symbolic-neural integration.</p>
      <p>In more detail, our approach combines preferential approaches to commonsense reasoning [14, 15,
16, 17, 18, 19, 20, 21, 22] with the Linear Time Temporal Logic (LTL) [23]. Preferential extensions of
LTL with defeasible temporal operators have been recently studied to enrich temporal formalisms with
non-monotonic reasoning features, by considering defeasible versions of the LTL operators [24, 25, 26].
In this regard, we follow a diferent route, adding the standard LTL operators to a conditional logic with
typicality, an approach similar to the one pursued for Description Logics (DLs), through an extension of
the temporal description logic LTLℒ [27] with the typicality operator [28]. As in the Propositional
Typicality Logic (PTL) by Booth et al. [29] (and in the DLs with typicality [30]) the conditionals will be
formalized based on material implication plus a typicality operator T. The typicality operator allows for
the definition of conditional implications T( ) →  , meaning that “normally if  holds,  holds". They
correspond to conditional implications  |∼  in KLM logics [17, 19]. In the paper, we will consider a
multi-preferential logic, where preferences are associated to aspects (and to arguments).</p>
      <p>The structure of the paper is as follows. Section 2 provides the necessary background on gradual
argumentation and two-valued multi-preferential conditional logic. In Section 3, we show how such
logic can be instantiated for reasoning on argumentation graphs. Section 4 introduces the temporal
extension of the logic, and Section 5 describes how it can be instantiated to model temporal aspects of
gradual argumentation. Section 6 concludes and discusses future directions.</p>
    </sec>
    <sec id="sec-2">
      <title>2. Preliminaries</title>
      <p>In this section we provide preliminaries on gradual argumentation semantics and on a two-valued
multi-preferential semantics for conditionals.</p>
      <sec id="sec-2-1">
        <title>2.1. Gradual argumentation semantics</title>
        <p>In this following, we shortly recap gradual argumentation semantics, following Baroni, Rago and Toni
[6, 7], and consider a specific semantic from [31, 32, 13].</p>
        <p>As in the Quantitative Bipolar Argumentation Framework (QBAF) by Baroni et al. [6, 7], we let the
domain of argument interpretation be a set , equipped with a preorder relation ≤ . In the literature, this
assumption is considered general enough to include the domain of argument valuations in most gradual
argumentation semantics [3, 33, 4, 34, 5, 6, 8, 11]. We do not assume that  contains a minimum element
and a maximum element. If they exist, we denote them by 0 and 1 (or simply 0 and 1), respectively.
If not, we will add the two elements 0 and 1 at the bottom and top of the values in , respectively.
For the definition of an argumentation graph, we consider the definition of edge-weighted QBAF by
Potyka [11], for a generic domain .</p>
        <p>We let a weighted argumentation graph to be a quadruple  = ⟨, ℛ,  0,  ⟩, where  is a set of
arguments, ℛ ⊆  ×  a set of edges, the base score function  0 :  →  assigns a base score to
arguments, and  : ℛ → R is a weight function assigning a positive or negative weight to edges. An
example of argumentation graph is in Figure 1, where a base score is not given.</p>
        <p>A ir (, ) ∈ ℛ is regarded as a support of argument  to argument  when the weight  (, ) is
positive and as an attack of argument  to argument  when  (, ) is negative.
argument valuation .</p>
        <p>
          The properties of edge-weighted argumentation graphs with weights in the interval [
          <xref ref-type="bibr" rid="ref1">0, 1</xref>
          ] have been
studied in [11] as well as in the gradual semantics framework by Amgoud and Doder [8].
        </p>
        <p>Whatever semantics  is considered for an argumentation graph , we will assume that the semantics
 identifies a set Σ  of many-valued labellings (also called strength functions, or weightings) of the graph
 over a domain of argument valuation . A many-valued labelling  of  over  is a total function
 :  → , which assigns to each argument an acceptability degree (or a strength) in the domain of</p>
        <p>When, in the following, we want to consider a set of possible values for the initial score of
Σ 0 = { 01,  02, . . . ,  0} is a finite set of possible initial scores .
arguments, we will represent the argumentation graph  as a triple  = (, ℛ, Σ 0,  ), where</p>
      </sec>
      <sec id="sec-2-2">
        <title>2.2. The  -coherent semantics</title>
        <p>argument  has neither supports nor attacks.</p>
        <p>
          Let us recall the definition of the  -coherent semantics of an argumentation graph  [13]. We let 
be the interval [
          <xref ref-type="bibr" rid="ref1">0, 1</xref>
          ] or the finite set  = {0, 1 , . . . , − 1 ,  }, for an integer  ≥ 1. Given a weighted
argumentation graph  = ⟨, ℛ,  0,  ⟩, we let R− (A) = {B | (B , A) ∈ ℛ}. When R− (A) = ∅,
 ) to all arguments  ∈  such that R− (Ai ) ̸= ∅, as follows:
        </p>
        <p>For a weighted graph  = ⟨, ℛ,  0,  ⟩ and a many-valued labelling  , the weight   on  is
defined as a partial function   :  → R, assigning a positive or negative support (relative to labelling
 () =</p>
        <p>∑︁
∈− ()
 ( , )  ( )
 () is left undefined when R− (Ai ) = ∅.
 : R → , a  -coherent many-valued labelling  of  is defined as follows:</p>
        <sec id="sec-2-2-1">
          <title>Definition 1.</title>
          <p>Given a weighted argumentation graph  = ⟨, ℛ,  0,  ⟩ and a non-decreasing function
 () =
︂{  ( ())
 0()
otherwise
for all Ai ∈  s.t. R− (Ai ) ̸= ∅
initial score in Σ 0.</p>
          <p>The semantics is a perceptron-like semantics which has been inspired by some preferential semantics
for weighted KBs developed in [35, 10], and has some relations with the semantics proposed by Potyka
[11] for interpreting neural networks (see [13] for comparisons). In this perceptron like view, the
argumentation graph plays the role of a (possibly recurrent) multilayer network, where arguments
 correspond to units, edges (with their weights) correspond to synaptic connections between units,
 () corresponds to the induced local field of unit , and  corresponds to the activation function.
The acceptability degree of an argument  in a labelling  corresponds to the activity of unit  in
a stationary state of the network. We refer to [9, 13] for further details, including properties of the
semantics and comparisons with other argumentation semantics.</p>
          <p>We denote by Σ  the set of all the  -coherent many-valued labelling  of  = ⟨, ℛ,  ⟩, for all
the possible choices of the initial score; by Σ 0 the set of the  -coherent many-valued labelling  for
the initial score  0, and by Σ Σ0 the set of the  -coherent many-valued labelling  for all the values of
Example 1. In the  -coherent semantics for the weighted argumentation graph  in Figure 1, in the
ifnitely-valued case with</p>
          <p>= , for  = 5, with  being the approximation in  of the logistic function,
Σ  contains 36 many-valued  -coherent labellings, while, for  = 9, Σ  contains 100  -coherent labellings.
In this case, there is a labelling for each combination of values of the base score for 2 and 6. For instance,</p>
          <p>= (3/5, 0, 3/5, 3/5, 1/5, 0) (meaning that  (1) = 3/5,  (2) = 0, and so on) is a many-valued
 -coherent labelling of  for  = 5.
(1)
(2)</p>
          <p>Above, the notion of  -coherent many-valued labelling of  is defined through a set of equations,
as in Gabbay’s equational approach to argumentation networks [36]. A definition of the  -coherent
semantics can also be given, in the style of the gradual semantics in the framework by Amgoud and
Doder [8]. We refer to [13] for details and for a discussion of the properties of the semantics. In
particular, one cannot assume that, for an initial score  0, there is a unique strength function  (a
unique  -coherent labelling).</p>
        </sec>
      </sec>
      <sec id="sec-2-3">
        <title>2.3. A two-valued multi-preferential semantics for conditionals</title>
        <p>In the following we recall the multi-preferential semantics from [37], and slightly extend it.</p>
        <p>As mentioned in the introduction, the conditional logic extends a propositional language  with a
typicality operator T, following the approach used in the description logic ℒ + T [38] as well as in
the Propositional Typicality Logic (PTL) [29]. Intuitively, “a sentence of the form T( ) is understood
to refer to the typical situations in which  holds" [29]. As in PTL [29], the typicality operator cannot
be nested. When an implication has the form T( ) →  , it is called a defeasible implication, whose
meaning is that “normally, if  then  ”. An implication  →  is called strict, if it does not contain
occurrences of the typicality operator.</p>
        <p>The KLM preferential semantics [17, 19, 16] exploits a single preference relation between worlds: a
set of worlds  , with their valuation and a preference relation &lt; among worlds (where  &lt; ′ means
that world  is more normal than world ′). A conditional  |∼  is satisfied in a KLM preferential
interpretation, if  holds in all the most normal worlds satisfying , i.e., in all &lt;-minimal worlds
satisfying . Here, instead, we consider a multi-preferential semantics, where preference relations are
associated with distinguished propositional formulas 1, . . . ,  (called distinguished propositions in the
following). In the semantics, a preference relation will be associated with each distinguished proposition
, where  &lt; ′ means that world  is less atypical than world ′ concerning aspect/property 
(e.g.,  &lt;student ′ means that  describes a less atypical situation for a student than ′).</p>
        <p>In the following we will consider finite KBs over a set Prop of propositional variables, and a finite set of
distinguished propositions 1, . . . ,  (propositional formulas over Prop). Preferential interpretations
are equipped with a set of worlds  and a finite set of preference relations &lt;1 , . . . , &lt; , where, for
each distinguished proposition , &lt; is a strict partial order on the set of worlds  . For the moment,
we assume that, in any typicality formula T(),  is a distinguished proposition.</p>
        <sec id="sec-2-3-1">
          <title>Definition 2.</title>
          <p>A (multi-)preferential interpretation is a triple ℳ = ⟨ , {&lt; }, ⟩ where:
∙  is a non-empty set of worlds;
∙ each &lt; ⊆  ×  is an irreflexive and transitive relation on  ;
∙  :  →− 2Prop is a valuation function, assigning to each world  a set of propositional
variables in Prop.</p>
          <p>A ranked interpretation is a (multi-)preferential interpretation ℳ = ⟨ , {&lt; }, ⟩ for which all
preference relations &lt; are modular, that is: for all , , , if  &lt;  then  &lt;  or  &lt; . A
relation &lt; is well-founded if it does not allow for infinitely descending chains of worlds 0, 1, 2, . . .,
with 1 &lt; 0, 2 &lt; 1, etc. The valuation  is inductively extended to all formulae:
ℳ,  |= ⊤</p>
          <p>ℳ,  ̸|= ⊥
ℳ,  |=  if  ∈ (), for all  ∈ Prop
ℳ,  |=  ∧  if
ℳ,  |=  ∨  if
ℳ,  |= ¬ if
ℳ,  |=  →  if
ℳ,  |= T() if
ℳ,  |=  and ℳ,  |= 
ℳ,  |=  or ℳ,  |= 
ℳ,  ̸|=</p>
          <p>ℳ,  |=  implies ℳ,  |= 
ℳ,  |=  and ∄w ′ ∈  s.t. w ′ &lt;Ai w and ℳ, ′ |= .</p>
          <p>Whether T() is satisfied at a world  or not also depends on the other worlds of the interpretation
ℳ. Restricting our consideration to modular interpretations, leads to the notions of satisfiability and
validity of a formula in the ranked (or rational) multi-preferential semantics. Diferently from [ 37] (and
from KLM semantics [17, 19]), here we do not assume well-foundedness of the preference relations.</p>
          <p>An implication of the form T() → , with  in ℒ, corresponds to a conditional  |∼  in
KLM logics [17]. It can be easily proven that, when all the preference relations &lt; coincide with
a single well-founded preference relation &lt;, a multi-preferential interpretation ℳ corresponds to a
KLM preferential interpretation, and a defeasible implication T() →  (with  and  in ℒ) has the
semantics of a KLM conditional  |∼ . The multi-preferential semantics is a generalization of the
KLM preferential semantics.</p>
          <p>Given a preferential interpretation ℳ, a formula  is satisfied in ℳ if ℳ,  |=  for some world
 ∈ . A formula  is valid in ℳ (written ℳ |=  ) if ℳ,  |=  , for all the worlds  ∈ . A
formula  is valid if  is valid in all the preferential interpretations ℳ.</p>
          <p>Let a knowledge base  be a set of (strict or defeasible) implications. A preferential model of  is
a multi-preferential interpretation ℳ such that ℳ |=  → , for all implications  →  in .
Given a knowledge base , we say that an implication  →  is preferentially entailed from  if
ℳ |=  →  holds, for all preferential models ℳ of . We say that  →  is rationally entailed from
 if ℳ |=  →  holds, for all ranked models ℳ of .</p>
          <p>It is well known that preferential entailment and rational entailment are weak. As with the rational
closure [19] and the lexicographic closure [39] for KML conditionals, also in the multi-preferential case
one can strengthen entailment by restricting to specific preferential models, based on some closure
constructions, which allow to define the preference relations &lt; from a knowledge base , e.g., by
exploiting the ranks or weights of conditional implications, when available [40, 41, 10].</p>
        </sec>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>3. A two-valued preferential interpretation of gradual semantics</title>
      <p>
        In [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ], we have defined a preferential interpretation of an argumentation graph  under a gradual
argumentation semantics , based on the many-valued conditional logic with a multi-preferential
semantics. In this section, we construct a conditional interpretation of an argumentation graph  under
a gradual semantics , based on a two-valued conditional logic with typicality.
      </p>
      <p>As we have seen, the semantics  of  can then be regarded, abstractly, as a pair (, Σ ): a domain
of argument valuation  and a set of labellings Σ  over the domain.</p>
      <p>If we consider the set of arguments  as propositional variables, each labelling  can be regarded as
a world  ∈  in a many-valued preferential interpretation ℳ which contains a preference relation
&lt; , for each argument  (here we are assuming that the single arguments 1, . . . ,  correspond to
the distinguished propositions).</p>
      <p>More precisely, a gradual semantics (, Σ ) of an argumentation graph  can be associated with a
preferential interpretation ℳ = ⟨, {&lt;1 , . . . , &lt; }, ⟩, defined by letting:
-  = { |  ∈ Σ }
- for all the arguments  ∈ , and a threshold value  ∈ :
( , ) =
︂{ 0
1
if  (Ai ) ≤ t
otherwise
(3)
- for all the arguments  ∈ , and worlds  ,  ′ ∈ :</p>
      <p>
        &lt;  ′ if  () &gt;  ′()
The choice of the threshold depends on the semantics and on the domain. For instance, for the domain
 = [
        <xref ref-type="bibr" rid="ref1">0, 1</xref>
        ], one may fix the threshold , e.g., to be 0 or 0.5. For a domain  = R, one may take  = 0.
When evaluating the typical worlds (labellings) for , only the worlds in which  has a strength
above the threshold need to be considered. The preference relation with respect to argument  is
induced by the strength of the argument  in the diferent labellings.
      </p>
      <p>Example 2. For instance, referring to the argumentation graph in Example 1, the labelling (strength
function)  = (3/5, 0, 3/5, 3/5, 1/5, 0) gives rise to a world  in the preferential interpretation ℳ
of the graph. Assuming a threshold  = 2/5, we have ( , 1) = ( , 3) = ( , 4) = 1 (as
 (1) &gt; ,  (3) &gt;  and  (4) &gt; ), while ( , 2) = ( , 5) = ( , 6) = 0.</p>
      <p>Furthermore, for a labelling  ′ ∈ Σ  such that  ′(3) = 4/5, we will have:  ′ &lt;3  , as
 ′(3) &gt;  (3). That is, labelling  ′ represents a more typical situation in which argument 3 holds,
with respect to labelling  .</p>
      <sec id="sec-3-1">
        <title>3.1. Conditionals for explanation and boolean combination of arguments</title>
        <p>Once a preferential interpretation ℳ of an argumentation graph  with respect to a gradual semantics
, has been constructed, such interpretation can be used in the verification of strict and conditional
graded implications (by checking their validity in the model ℳ), for explanation, e.g., by validating
conditional relations between arguments.</p>
        <p>For instance, given a weighted argumentation graph  describing the rules for assigning loans, e.g.,
involving the arguments living _in_town, young and granted _loan, and a gradual semantics , one
may want to verify the property</p>
        <p>T(granted _loan) → living _in_town ∧ young
(normally the loan is granted to people living in town and being young) or the property
living _in_town ∧ young → T(granted _loan)
(living in town and being young implies that normally the loan is granted). The implications above can
be checked for validity over the preferential interpretation ℳ, constructed from the set of labellings
Σ  of the graph  in the semantics .</p>
        <p>Let us continue the example concerning the argumentation graph in Figure 1, under the  -coherent
argumentation semantics.</p>
        <p>Example 3. As mentioned before, for the weighted argumentation graph in Figure 1, in the  -coherent
argumentation semantics there are 36 labellings in case of a domain  with  = 5. Since 2 supports
3, which in turn attacks 5, some relation can be expected between 2 and 5. Assuming a threshold
 = 2/5, the following conditional implication turns out to be valid in the interpretation ℳ:
T(2) → ¬5</p>
        <p>T(1 ∨ 2) → ¬5
that is, in the situations (labellings) which maximize the acceptability of argument 2, argument ¬5
holds. The corresponding strict implication 2 → ¬5 does not hold.</p>
        <p>In this example, we may wonder whether model ℳ also validates the implication:
It turns out, however, that the last conditional implication is outside the language we have defined.</p>
        <p>So far we have assumed that the distinguished propositions correspond to single arguments. We lift
this condition and allow typicality formulas T(), with  a boolean combination of arguments, to
include typicality formulas as T(1 ∨ 2) in the example above, and also the typicality formula in the
conditional implication:</p>
        <p>T(living _in_town ∧ young ) → granted _loan
To deal with these conditionals, we have to extend preferential interpretations by allowing preference
relations &lt; associated with boolean combinations of arguments , and generalizing the semantic
condition of typicality formulas (in Definition 2) to any boolean combination of arguments , as follows:
ℳ,  |= T() if</p>
        <p>ℳ,  |=  and ∄w ′ ∈  s.t. w ′ &lt;A w and ℳ, ′ |= 
For instance, for evaluating T(1 ∨ 2) → ¬5, we need preference relation &lt;1∨2 .</p>
        <p>The definition of of the preference relation &lt; for a boolean combination of arguments can rely on
the strength of the atomic arguments in the gradual semantics. The strength of boolean arguments
in a labelling can be defined inductively from the strength of the atomic arguments  in the gradual
semantics by exploiting suitable truth degree functions ⊗ , ⊕ , ⊖ in , as follows:
 (¬) = ⊖  ()
 ( ∧ ) =  () ⊗  ()
 ( ∨ ) =  () ⊕  ()
where  and  are boolean combinations of arguments.</p>
        <p>
          When  is [
          <xref ref-type="bibr" rid="ref1">0, 1</xref>
          ] or the finite truth space  = {0, 1 , . . . , − 1 ,  }, for an integer  ≥ 1, ⊗ , ⊕ and
⊖ can be chosen as a triangular norm (or t-norm), a triangular co-norm (or s-norm) and a negation
function in some system of many-valued logic [42]. For instance, in the following, for the  -coherent
semantics, we let  ⊗  = {, },  ⊕  = {, }, and ⊖  = 1 − .
        </p>
        <p>Then, the preference relation &lt; can be defined as:</p>
        <p>&lt;  ′ if  () &gt;  ′()
for all worlds  ,  ′ ∈ .</p>
        <p>We can reconsider the previous example, based on this generalization of the preferential semantics.
Example 4. Based on the choice of truth degree functions above, one can prove that the conditional
implication T(1 ∨ 2) → ¬5 is valid in the preferential interpretation of the argumentation graph 
in Figure 1 under the  -coherent semantics, while the strict implication 1 ∨ 2 → ¬5 is not valid.</p>
        <p>
          Note that the idea of interpreting the strength function  as a valuation in a many-valued logic, was
previously used in many-valued preferential interpretations [
          <xref ref-type="bibr" rid="ref1">1, 13</xref>
          ]. Instead, here it has been exploited
in the construction of a two-valued preferential interpretation ℳ.
        </p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. A temporal conditional multi-preferential logic</title>
      <p>In this section, we extend the two-valued conditional logic in Section 2.3 with the operators of the
Linear Time Temporal Logic (LTL) [23].</p>
      <p>Compared with the preferential semantics above, the semantics of  T also considers the temporal
dimension, through a set of time points in N. The valuation function assigns, at each time point  ∈ N,
a truth value to each propositional variable in a world  ∈ ; the preference relations &lt; (with
respect to each distinguished proposition ) are relative to time points. Evolution in time may change
the valuation of propositions at the worlds, and it may also change the preference relations between
worlds ( might represent a typical situation for a student at time point 0, but not at time point 50).</p>
      <p>A temporal (multi-)preferential interpretation (or  T interpretation) is a triple ℐ =</p>
      <sec id="sec-4-1">
        <title>Definition 3.</title>
        <p>⟨, {&lt; }∈N, ⟩ where:
•  is a non-empty set of worlds;
• for each  and  ∈ N, &lt; ⊆  ×  is an irreflexive and transitive relation on ;
•  : N ×  →− 2Prop is a valuation function assigning, at each time point , a set of propositional
variables in Prop to each world  ∈ .</p>
        <p>For  ∈  and  ∈ N, (, ) is the set of the propositional variables which are true in world  at
time point . If there is no ′ ∈  s.t. ′ &lt; , we say that  is a normal situation for  at time point
.</p>
        <p>Given an  T interpretation ℐ = ⟨, {&lt; }∈N, ⟩, we define inductively the truth value of a
formula  in a world  at time point  (written ℐ, ,  |= ), as follows:
ℐ, ,  |= ⊤</p>
        <p>ℐ, ,  ̸|= ⊥
ℐ, ,  |=  if  ∈ (, ), for all  ∈ Prop
ℐ, ,  |=  ∧  if ℐ, ,  |=  and ℐ, ,  |= 
ℐ, ,  |=  ∨  if ℐ, ,  |=  or ℐ, ,  |= 
ℐ, ,  |= ¬ if ℐ, ,  ̸|= 
ℐ, ,  |=  →  if ℐ, ,  |=  implies ℐ, ,  |= 
ℐ, ,  |=  if ℐ,  + 1,  |= 
ℐ, ,  |= ◇ if there is an  ≥  such that ℐ, ,  |= 
ℐ, ,  |= □ if for all  ≥ , ℐ, ,  |= 
ℐ, ,  |=   if there is an  ≥  such that ℐ, ,  |=  and,</p>
        <p>for all  such that  ≤  &lt; , ℐ, ,  |= 
ℐ, ,  |= T() if ℐ, ,  |=  and ∄w ′ ∈  s.t. w ′ &lt;nAi w and ℐ, , ′ |= .
Note that whether a world  represents a typical situation for  at a time point  depends on the
preference between worlds at time point .</p>
        <p>A temporal conditional KB is a set of  T formulas. We evaluate the satisfiability of a temporal
graded formula at the initial time point 0 of a temporal preferential interpretation ℐ.
Definition 4. An  T formula  is satisfied in a temporal preferential interpretation ℐ = ⟨, {&lt;
}∈N, ⟩ if ℐ, 0,  |=  , for some world  ∈ . An  T formula  is valid in a temporal preferential
interpretation ℐ = ⟨, {&lt; }∈N, ⟩ if ℐ, 0,  |=  , for all worlds  ∈ . An  T formula  is
valid, if  is valid in all temporal preferential interpretations ℐ. An  T formula  is satisfiable , if  is
satisfied in some temporal preferential interpretation ℐ.</p>
        <p>It can be shown that the problem of deciding the satisfiability of an  T formula  can be
polynomially reduced to the problem of deciding the satisfiability of a concept  in the description
ltohgeictypicalTitℒyoipnetrraotdour.cedinT[28],hwashbicehenexptreonvdesnthtoe bteemdpecoirdaalbdleeswcrhipetnioanfinliotegiscetofweℒll-f[o2u7n]dweidth
ℒ
preference relations &lt;1 , . . . , &lt; is considered, and concept inclusions are regarded as global temporal
constraints. In turn, the decidability of concept satisfiability in  T relies on the result that concept
satisfiability for LTLℒ w.r.t. TBoxes is in ExpTime (and, actually,iℒtis ExpTime-complete), both with
expanding domains [43] and with constant domains [27].</p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>5. Towards a temporal conditional logic for gradual argumentation</title>
      <p>As for the non-temporal case, we aim at instantiating the two-valued temporal conditional logic
introduced in the previous section to the gradual argumentation setting, to make it suitable for capturing
the dynamics of strength functions in time.</p>
      <p>In Amgoud and Doder’s framework of gradual semantics [8], it is proven that a uniform iterative way
of calculating strengths of arguments can be applied to any semantics based on well-defined evaluation
methods, for which convergence is guaranteed.</p>
      <p>In the following, we consider an iterative formulation of the  -coherent semantics, and describe a
possible construction of a temporal interpretation for it. In particular, starting from an initial score  0,
one can iteratively define a sequence of labellings  0,  1,  2, ..., as follows:
 () =
︂{  0()
 ( − 1 ())
if R− (Ai ) = ∅
if R− (Ai ) ̸= ∅
(4)
In the general case, for the  -coherent semantics one cannot guarantee that the sequence  0,  1,  2, ...,
starting from an initial score  0, converges to some  -coherent labelling, unless the argumentation
graph  is acyclic. Convergence conditions for edge-weighted QBAFs have been studied by Potyka,
both in the discrete and in the continuous case [11].</p>
      <p>Although the sequence of labellings  0,  1,  2, ..., may not converge, one may be interested in
verifying temporal properties over the sequence of labellings (or a finite stretch of it). More generally,
one may be interested in considering a finite set Σ 0 of possible initial score functions { 01,  02, . . . ,  0}.
The associated sequences  0 ,  1 ,  2 , ..., one for each initial score function  0 , determine a set of runs,
from which a temporal preferential interpretation ℐ of the argumentation graph  can be constructed.</p>
      <p>In the sequence of labellings  0 ,  1 ,  2 , ... obtained from each initial score function  0 ∈ Σ 0, the
labelling   is the one obtained from  0 at iteration .</p>
      <p>Let the set of arguments  be the set of propositional variables of the temporal conditional logic. We
can build a temporal preferential interpretation ℐ = ⟨, {&lt; }∈N, ⟩ of an argumentation graph ,
from a set of initial score functions Σ 0, by introducing a world  ∈  for each initial score function
 0 in Σ 0. The valuation of propositions  in a world  at time point , will be determined by the
strength  () of the argument  in the labelling  .</p>
      <p>More precisely we define a temporal preferential interpretation ℐ = ⟨, {&lt; }∈N, ⟩ of an
argumentation graph , with respect to Σ 0, by letting:
-  = { |  0 ∈ Σ 0}
- for all the arguments  ∈ , and a threshold value  ∈ :
- for all the arguments  ∈ , and worlds ℎ,  ∈ :</p>
      <p>∈ (,  ) if  () &gt; ;
 &lt; ℎ if  () &gt;  ℎ().</p>
      <p>Note that a temporal many-valued interpretation ℐ = ⟨, {&lt; }∈N, ⟩ can be seen as a sequence
of (non-temporal) preferential interpretations ℳ0, ℳ1, ℳ2, . . ., where each ℳ = ⟨, {&lt; }, ⟩
is constructed from all the labelling Σ  of the argumentation graph  at the iteration  (one for each
initial score function in Σ 0), as for ℳ above.</p>
      <p>Once a temporal preferential interpretation ℐ has been constructed, the validity of temporal
conditional formulas over arguments, such as □(T(A1 ) → 2 A3 ∨ 3), can be verified over the
constructed preferential interpretation ℐ. In the loan example, for instance, one may want to check
whether normally, young people leaving in town are eventually granted a loan, i.e., T(living _in_town ∧
young ) → ◇granted _loan.</p>
      <p>For boolean combinations of arguments in typicality formulas, the non-temporal solution from
Section 3.1 extends naturally to the temporal case. Moreover, the approach described here is not limited
to the  -coherent semantics, but can also be adapted to other gradual argumentation semantics with
iterative formulations, such as those in [8, 11].</p>
    </sec>
    <sec id="sec-6">
      <title>6. Conclusions</title>
      <p>
        In [44], we introduced a many-valued temporal logic with typicality by extending the many-valued
conditional logic of [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ] with   operators. In this paper, we instead develop a two-valued conditional
logic with typicality for gradual argumentation, extending it to the temporal case with standard  
modalities. Compared to the many-valued setting, this framework is conceptually simpler yet still
supports expressive reasoning over argumentation graphs. In the non-temporal setting, this approach
enables verification of properties of argumentation graphs under diferent gradual semantics [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ]. For
the many-valued  -coherent semantics [32, 13], we have also provided ASP encodings to check graded
conditional implications over atomic and boolean argument combinations. Extending these ASP-based
techniques to the two-valued temporal case is a natural direction for future work. The temporal
extension introduced here enables reasoning about transient properties in the evolution of argument
strength, for instance over sequences of labellings from iterative updates. Such reasoning supports
model checking or entailment verification of dynamic behaviors, and may aid explainable AI where
argumentation evolves over time.
      </p>
      <p>A particularly promising application lies in the analysis of neural networks. Indeed, a multilayer
neural network can be interpreted as a weighted knowledge base [9, 10] or as a weighted argumentation
graph [12, 11], given the strong semantic relationships also explored in [13]. In the many-valued setting,
conditional weighted KBs have already been shown to capture the stationary states of such networks (or
suitable approximations thereof) [35, 10, 13], supporting post-hoc symbolic reasoning and verification.
The addition of a temporal dimension, as proposed here, opens the way to verifying properties of
dynamic behavior — such as how activations evolve, how information propagates, or how explanatory
patterns shift over time. From a logical perspective, our approach ofers an alternative to other defeasible
temporal logics that enrich temporal operators directly, such as those studied in [25, 45]. While those
frameworks include tableaux methods and address decidability of fragments with defeasible temporal
connectives [24], our logic maintains standard   operators and encodes defeasibility entirely through
temporal evolution of preferential structures (namely, by allowing preference relations among worlds
to change over time). This yields a clean separation between temporal and nonmonotonic aspects,
which may facilitate integration with other symbolic reasoning tools. Finally, our work contributes to
neuro-symbolic integration [46, 47, 48] by providing a principled framework that links typicality-based
conditional logic with neural models in a temporally dynamic and semantically transparent way.</p>
      <p>Directions for further research include: developing ASP encodings for the temporal logic proposed
here; studying the decidability and complexity of fragments of the logic; investigating convergence
and stability in iterative dynamics; applying the framework to explainability of evolving argumentation
graphs and time-dependent neural-symbolic systems.</p>
    </sec>
    <sec id="sec-7">
      <title>Acknowledgments</title>
      <p>This research was partially supported by INDAM-GNCS. Mario Alviano was partially supported by
the Italian Ministry of University and Research (MUR) under PRIN project PRODE “Probabilistic
declarative process mining”, CUP H53D23003420006, under PNRR project FAIR “Future AI Research”,
CUP H23C22000860006, under PNRR project Tech4You “Technologies for climate change adaptation
and quality of life improvement”, CUP H23C22000370006, and under PNRR project SERICS “SEcurity
and RIghts in the CyberSpace”, CUP H73C22000880001; by the Italian Ministry of Health (MSAL) under
POS projects CAL.HUB.RIA (CUP H53C22000800006) and RADIOAMICA (CUP H53C22000650006); by
the Italian Ministry of Enterprises and Made in Italy under project STROKE 5.0 (CUP B29J23000430005);
under PN RIC project ASVIN “Assistente Virtuale Intelligente di Negozio” (CUP B29J24000200005);
and by the LAIA lab (part of the SILA labs). Mario Alviano is member of Gruppo Nazionale Calcolo
Scientifico-Istituto Nazionale di Alta Matematica (GNCS-INdAM).</p>
    </sec>
    <sec id="sec-8">
      <title>Declaration on Generative AI</title>
      <p>The author(s) have not employed any Generative AI tools.
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