S4 References S4 logical system Ask Anything Homework Help Written by The Information Architects of Encyclopaedia Britannica The Information Architects maintain a master list of the topics included in the corpus of EncyclopΓ¦dia Britannica, and create and manage the relationships between them. The Information Architects of Encyclopaedia Britannica Britannica AI Ask Anything Learn about this topic in these articles: formal logic/ Alternative systems of modal logicβ¦ to T is known as S4; that obtained by adding Mp β LMp to T is known as S5; and the addition of p β LMp to T gives the Brouwerian system (named for the Dutch mathematician L.E.J. Brouwer), here called B for short. Read Moreβ¦ to T is known as S4; that obtained by adding Mp β LMp to T is known as S5; and the addition of p β LMp to T gives the Brouwerian system (named for the Dutch mathematician L.E.J. Brouwer), here called B for short. Read More