<story><title>The science of Westworld</title><url>https://blog.plan99.net/the-science-of-westworld-ec624585e47#.th6i2yuzb</url></story><parent_chain><item><author>sssparkkk</author><text>&amp;quot;Lily is a swan. Lily is white. Bernhard is green. Greg is a swan.&amp;quot; -&amp;gt; &amp;quot;What color is Greg? Answer: white&amp;quot;&lt;p&gt;At the risk of sounding somewhat stupid, but shouldn&amp;#x27;t this contain &amp;quot;Swans are white&amp;quot; for it to be a correct answer?</text></item></parent_chain><comment><author>tfm</author><text>If we&amp;#x27;re limiting ourselves to deductive reasoning, then yes – the facts as stated do not give enough information to deduce that Greg must be white.&lt;p&gt;If instead we use abductive inference, we might seek the simplest and most likely explanation given our universe of observations. Sherlock Holmes was a big fan of abduction!&lt;p&gt;Much of real-world reasoning is abductive to a greater or lesser extent. There is a well-known joke about some motley band of engineers, logicians, mathematicians, statisticians, etc etc catching a train through the Highlands. They see a black sheep, the engineer says &amp;quot;look, all sheep in Scotland are black!&amp;quot;, the statistician says &amp;quot;no, you can&amp;#x27;t say that – just that MOST sheep in Scotland are black&amp;quot;, another says &amp;quot;no, we can only say that at least ONE sheep is black&amp;quot;, another says &amp;quot;no, it&amp;#x27;s only black on at least one side&amp;quot;, then the one you&amp;#x27;re stuck next to at the party says &amp;quot;you&amp;#x27;re all wrong, we can only say that at least one sheep in Scotland is black on at least one side at least some of the time&amp;quot;. The last statement is fully deductive; the rest of them are abductive, and more-or-less useful.</text></comment>
<story><title>The science of Westworld</title><url>https://blog.plan99.net/the-science-of-westworld-ec624585e47#.th6i2yuzb</url></story><parent_chain><item><author>sssparkkk</author><text>&amp;quot;Lily is a swan. Lily is white. Bernhard is green. Greg is a swan.&amp;quot; -&amp;gt; &amp;quot;What color is Greg? Answer: white&amp;quot;&lt;p&gt;At the risk of sounding somewhat stupid, but shouldn&amp;#x27;t this contain &amp;quot;Swans are white&amp;quot; for it to be a correct answer?</text></item></parent_chain><comment><author>mazsa</author><text>I think you are right (metamath):&lt;p&gt;$( &amp;lt;MM&amp;gt; &amp;lt;PROOF_ASST&amp;gt; THEOREM=whiteswans LOC_AFTER=&lt;p&gt;* Assume it is provable that ( l e. S &amp;#x2F;\ l e. W ) implies for all l ( l e. S &amp;#x2F;\ l e. W ), and assume that g e. S . Then it is provable that if ( l e. S &amp;#x2F;\ l e. W ) then g e. W .&lt;p&gt;h1::whiteswans.1   |- (  ( l e. S &amp;#x2F;\ l e. W ) -&amp;gt; A. l ( l e. S -&amp;gt; l e. W ) )&lt;p&gt;h2::whiteswans.2   |- g e. S&lt;p&gt;3:1:bnj1361        |- ( ( l e. S &amp;#x2F;\ l e. W ) -&amp;gt; S C_ W )&lt;p&gt;5:3:sseld          |- ( ( l e. S &amp;#x2F;\ l e. W ) -&amp;gt; ( g e. S -&amp;gt; g e. W ) )&lt;p&gt;qed:2,5:mpi        |- ( ( l e. S &amp;#x2F;\ l e. W ) -&amp;gt; g e. W )&lt;p&gt;$=    ( cv wcel wa bnj1361 sseld mpi ) DGZAHMCHIZBGZAHOCHFNACONDACEJKL $.&lt;p&gt;$d S l&lt;p&gt;$d W l&lt;p&gt;$)</text></comment>