System K4


Sobociński's original K4

[Sobociński, 1964a]

System K4 (Sobociński) is the system S4.4 plus the axiom MS [LMp=>MLp] [Zeman, 1973, p249] [Hughes & Cresswell, 1968, p345]

Later, this K4 appears in the literature

System K4 (K+4) is the system K plus the axiom 4 [Huges&Cresswell, 1996, p362]


Thanks to all who provided literature pointers to sort out the two K4 systems. (: Even if it meant I did a lot of rewriting. :) thanks especially to Max Cresswell and Ken Pledger who (once again) took time out to point me to the correct sources.

Go to ...

© Copyright 2005, by John Halleck, All Rights Reserved.
This page is
This page was last modified on July 15th, 2008.