S4

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S4

logical system

Learn about this topic in these articles:

modal logic

In formal logic: Alternative systems of modal logic
… to T is known as S4; that obtained by adding Mp ⊃ LMp to T is known as S5; and the addition of p ⊃ LMp to T gives the Brouwerian system (named for the Dutch mathematician L.E.J. Brouwer), here called B for short.
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