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Wed 4 Aug, 2010 03:09 am
Perform a predicate truth tree analysis on the following propositions, pairs of propositions, and sequents. Show the sufficiently decompose truth tree and your analysis of the logical property in question.
1: Test for Contingency, Inconsistency, Tautology
(Ex)(Ay)(Dyx -> ~Dxy)
(SOME x)(ANY y)(IF y D x THEN x NOT D y)
Contingency Inconsistency Tautology
2: Test for Logical Consistency
(Ex)(Sx & Wx) (Ay)~(Wy v Sy)
(SOME x)(BOTH x S AND x W) (ANY y) NOT(EITHER y W OR y S)
Logically Consistent Logically Inconsistent
3: Test for Deductive Validity
(Ax)(Ay)(Mxy -> Nxy) ├ (Ax)(Ay)(Mxy -> (Nxy & Nyx))
(ANY x)(ANY y)(IF x M y THEN x N Y) THUS (ANY x)(ANY y)(IF x M y THEN (BOTH x N Y AND y N x))
Deductively Valid Deductively Invalid
4: Test for Deductive Validity
(Ax)(Sx -> (Fx v Gx)), (Ex)(Sx & ~Gx)├ (Ew)Fw
(ANY x)(IF x S THEN (EITHER x F Or x G)), (SOME y)(BOTH y S AND y NOT G) THUS (SOME x)(w F)
Deductively Valid Deductively Invalid