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Ideas of GE Hughes/M Cresswell, by Text
[New Zealand, fl. 1968, Professor at Wellington University, NZ.]
1968
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An Introduction to Modal Logic
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Ch.1
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p.10
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9540
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A 'value-assignment' (V) is when to each variable in the set V assigns either the value 1 or the value 0
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Ch.1
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p.15
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9541
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The Law of Transposition says (P→Q) → (¬Q→¬P)
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Ch.1
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p.19
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9543
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The rules preserve validity from the axioms, so no thesis negates any other thesis
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Ch.1
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p.19
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9544
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A system is 'weakly' complete if all wffs are derivable, and 'strongly' if theses are maximised
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