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        <p class="card-text">

Consider a first-order logical knowledge base that describes worlds
containing people, songs, albums (e.g., “Meet the Beatles”) and disks
(i.e., particular physical instances of CDs). The vocabulary contains
the following symbols:<br />

&gt; ${CopyOf}(d,a)$: Predicate. Disk $d$ is a copy of album $a$.

&gt; ${Owns}(p,d)$: Predicate. Person $p$ owns disk $d$.

&gt; ${Sings}(p,s,a)$: Album $a$ includes a recording of song $s$ sung by person $p$.

&gt; ${W