The system S0.9 is Lemmon's basis for S2, minus the rule "From |- L(a>b) infer L(La>Lb)":
© Copyright 2006, by John Halleck, All Rights Reserved.
This page is http://www.cc.utah.edu/~nahaj/logic/structures/systems/s0.9.html
This page was last modified on September 11th, 2006