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===Step 3 (Optional)===
 
===Step 3 (Optional)===
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<pre>
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At this juncture we might want to verify that the proposition corresponding to the type of <math>\operatorname{T}</math> is actually a theorem of classical propositional calculus. Since nothing can be a theorem of intuitionistic propositional calculus wihout also being a theorem of classical propositional calculus, this is a necessary condition of our work being correct up to this point. Although it is not a sufficient condition, classical theoremhood is easier to test and so provides a quick and useful check on our work.
At this juncture we might want to verify that the proposition corresponding
  −
to the type of T is actually a theorem of classical propositional calculus.
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Since nothing can be a theorem of intuitionistic propositional calculus
  −
wihout also being a theorem of classical propositional calculus, this
  −
is a necessary condition of our work being correct up to this point.
  −
Although it is not a sufficient condition, classical theoremhood
  −
is easier to test and so provides a quick and useful check on
  −
our work.
     −
In existential graph format, T has the following generic typing:
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In existential graph format, <math>\operatorname{T}</math> has the following generic typing:
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<pre>
 
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</pre>
    
And here is a classical logic proof of the type proposition:
 
And here is a classical logic proof of the type proposition:
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<pre>
 
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