This is Sobociński's original K4 system.
For the system called K4 and formed from system K + Axiom 4 See K4 (K+4)
System K4 (Sobociński) is the system S4.4 plus the axiom MS [LMp=>MLp] [Zeman, 1973, p249] [Hughes & Cresswell, 1968, p345]
© Copyright 2000, by John Halleck, All Rights Reserved.
This page is http://www.cc.utah.edu/~nahaj/logic/structures/systems/k4.sob.html
This page was last modified on July 15th, 2008.