The New Encyclopædia BritannicaEncyclopædia Britannica, 1983 - Encyclopedias and dictionaries |
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Page 41
Decision procedure with truth tables Construc- tion of valid wff's Axiom schemata Validity of wff's in three- valued logic Dubious. FR1 . A variable standing alone is a wff FR2 . If a is a wff , so is ~ a FR3 . If a and ẞ are wff's , ( a ...
Decision procedure with truth tables Construc- tion of valid wff's Axiom schemata Validity of wff's in three- valued logic Dubious. FR1 . A variable standing alone is a wff FR2 . If a is a wff , so is ~ a FR3 . If a and ẞ are wff's , ( a ...
Page 42
... wff's , a and ẞ , are said to be equiva- lents when a = ẞ is valid . ( The wff's a and ẞ are equiva- lents if and only if they have identical truth tables . ) The rule states that if any part of a wff is replaced by an equivalent of ...
... wff's , a and ẞ , are said to be equiva- lents when a = ẞ is valid . ( The wff's a and ẞ are equiva- lents if and only if they have identical truth tables . ) The rule states that if any part of a wff is replaced by an equivalent of ...
Page 43
... wff's are precisely those wff's of PC that can be built up from variables , D , and brackets alone . Formation rules 2 and 3 of II . Formation rules for PC are therefore replaced by the rule that if a and ẞ are wff's , ( a B ) is a wff ...
... wff's are precisely those wff's of PC that can be built up from variables , D , and brackets alone . Formation rules 2 and 3 of II . Formation rules for PC are therefore replaced by the rule that if a and ẞ are wff's , ( a B ) is a wff ...
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