let Y be non empty set ; for a being Function of Y,BOOLEAN
for G being Subset of (PARTITIONS Y)
for A, B being a_partition of Y st G is independent holds
Ex (('not' (All (a,A,G))),B,G) = Ex (('not' (All (a,B,G))),A,G)
let a be Function of Y,BOOLEAN; for G being Subset of (PARTITIONS Y)
for A, B being a_partition of Y st G is independent holds
Ex (('not' (All (a,A,G))),B,G) = Ex (('not' (All (a,B,G))),A,G)
let G be Subset of (PARTITIONS Y); for A, B being a_partition of Y st G is independent holds
Ex (('not' (All (a,A,G))),B,G) = Ex (('not' (All (a,B,G))),A,G)
let A, B be a_partition of Y; ( G is independent implies Ex (('not' (All (a,A,G))),B,G) = Ex (('not' (All (a,B,G))),A,G) )
A1:
'not' (All ((All (a,A,G)),B,G)) = Ex (('not' (All (a,A,G))),B,G)
by BVFUNC_2:18;
assume
G is independent
; Ex (('not' (All (a,A,G))),B,G) = Ex (('not' (All (a,B,G))),A,G)
hence
Ex (('not' (All (a,A,G))),B,G) = Ex (('not' (All (a,B,G))),A,G)
by A1, Th15; verum