Classical modal logic: Difference between revisions

Revision as of 02:05, 23 November 2010

Revision as of 12:05, 10 November 2012

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<math>\Diamond A \equiv \lnot\Box\lnot A</math>

which is also [[Deductive closure|closed]] under the rule

<math> A \equiv B \vdash \Box A\equiv\Box B.</math>