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Ideas of GE Hughes/M Cresswell, by Text

[New Zealand, fl. 1968, Professor at Wellington University, NZ.]

1968 An Introduction to Modal Logic
Ch.1 p.10 A 'value-assignment' (V) is when to each variable in the set V assigns either the value 1 or the value 0
Ch.1 p.15 The Law of Transposition says (P→Q) → (Q→P)
Ch.1 p.19 The rules preserve validity from the axioms, so no thesis negates any other thesis
Ch.1 p.19 A system is 'weakly' complete if all wffs are derivable, and 'strongly' if theses are maximised