LPL_2.3_2.4_lecture

LPL_2.3_2.4_lecture - Formal proofs with identity Whereas...

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Formal proofs with identity Whereas informal proofs may be done in a variety of ways, depending on the level of precision demanded by the audience at which the proof is aimed, the formal proofs we will do will all follow the same format. P Q R S 1 Justification 1 : : S n Justification n S Justification n + 1 We will use a Fitch-style system which places the premises of the argument above the Fitch bar and the conclusion and all supporting steps below the Fitch bar. Notice that to the right of each supporting step, a justification must be given. The reason such justification is necessary is that a rule must be cited in order to add each new step to a proof. If each supporting step in the proof is justified by a correct usage of a rule, then we can be certain that each step, including the conclusion, is a logical consequence of the given premises. Identity Introduction (= Intro): n = n The first rule we will use is Identity Introduction . Like its informal counterpart, which is the principle of reflexivity of identity, Identity Introduction allows us to introduce into
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This note was uploaded on 06/06/2011 for the course PHIL 110 taught by Professor ? during the Fall '06 term at South Carolina.

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LPL_2.3_2.4_lecture - Formal proofs with identity Whereas...

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