tweak to explanation of analogical reasoning

pkn.html

@@ -715,7 +715,7 @@ <h3>Reasoning with Implications</h3>
     <h3>Reasoning with Analogies</h3>
     <p>Analogies involve comparisons between things or objects where similarities in some respects can suggest the likelihood of similarities in other respects, for instance, in their respective properties and relationships, or in ways to solve related problems. Gentner and Markman proposed a basis for modelling analogies in terms of establishing a structural alignment based on common relational structure for two representations, where the stronger the match, the better the analogy, see [[[GENTNER]]].</p>
     <p>In some cases, the objects may have the same properties, in other cases, there is a systematic mapping between different properties, e.g., relating electric current to the flow of a liquid in a pipe, and correspondingly, voltage to pressure. If you know that flow increases with pressure, you can infer that current increases with voltage.</p>
-    <p>Analogical reasoning tests often take the form of A is to B as Y is to —, where students are asked to supply the missing term. This can be readily modelled using PKN, for example consider the query:</p>
+    <p>Analogical reasoning tests often take the form of A is to B as X is to —, where students are asked to supply the missing term. This can be readily modelled using PKN, for example consider the query:</p>
 
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