let Y be non empty set ; :: thesis: for a being Element of Funcs Y,BOOLEAN
for G being Subset of (PARTITIONS Y)
for A, B being a_partition of Y holds 'not' (All (All a,A,G),B,G) = Ex (Ex ('not' a),A,G),B,G
let a be Element of Funcs Y,BOOLEAN ; :: thesis: for G being Subset of (PARTITIONS Y)
for A, B being a_partition of Y holds 'not' (All (All a,A,G),B,G) = Ex (Ex ('not' a),A,G),B,G
let G be Subset of (PARTITIONS Y); :: thesis: for A, B being a_partition of Y holds 'not' (All (All a,A,G),B,G) = Ex (Ex ('not' a),A,G),B,G
let A, B be a_partition of Y; :: thesis: 'not' (All (All a,A,G),B,G) = Ex (Ex ('not' a),A,G),B,G
Ex ('not' (All a,A,G)),B,G = Ex (Ex ('not' a),A,G),B,G by BVFUNC_2:20;
hence 'not' (All (All a,A,G),B,G) = Ex (Ex ('not' a),A,G),B,G by BVFUNC_2:20; :: thesis: verum