let Y be non empty set ; :: thesis: for G being Subset of (PARTITIONS Y)
for a, u being Function of Y,BOOLEAN
for PA being a_partition of Y holds u 'imp' (Ex (a,PA,G)) '<' Ex ((u 'imp' a),PA,G)
let G be Subset of (PARTITIONS Y); :: thesis: for a, u being Function of Y,BOOLEAN
for PA being a_partition of Y holds u 'imp' (Ex (a,PA,G)) '<' Ex ((u 'imp' a),PA,G)
let a, u be Function of Y,BOOLEAN; :: thesis: for PA being a_partition of Y holds u 'imp' (Ex (a,PA,G)) '<' Ex ((u 'imp' a),PA,G)
let PA be a_partition of Y; :: thesis: u 'imp' (Ex (a,PA,G)) '<' Ex ((u 'imp' a),PA,G)
let z be Element of Y; :: according to BVFUNC_1:def 12 :: thesis: ( not (u 'imp' (Ex (a,PA,G))) . z = TRUE or (Ex ((u 'imp' a),PA,G)) . z = TRUE )
A1: z in EqClass (z,(CompF (PA,G))) by EQREL_1:def 6;
assume (u 'imp' (Ex (a,PA,G))) . z = TRUE ; :: thesis: (Ex ((u 'imp' a),PA,G)) . z = TRUE
then A2: ('not' (u . z)) 'or' ((Ex (a,PA,G)) . z) = TRUE by BVFUNC_1:def 8;
A3: ( (Ex (a,PA,G)) . z = TRUE or (Ex (a,PA,G)) . z = FALSE ) by XBOOLEAN:def 3;

now :: thesis: ( ( 'not' (u . z) = TRUE & (Ex ((u 'imp' a),PA,G)) . z = TRUE ) or ( (Ex (a,PA,G)) . z = TRUE & (Ex ((u 'imp' a),PA,G)) . z = TRUE ) )

per cases ( 'not' (u . z) = TRUE or (Ex (a,PA,G)) . z = TRUE ) by A2, A3, BINARITH:3;

case A4: 'not' (u . z) = TRUE ; :: thesis: (Ex ((u 'imp' a),PA,G)) . z = TRUE

(u 'imp' a) . z = ('not' (u . z)) 'or' (a . z) by BVFUNC_1:def 8
.= TRUE by A4, BINARITH:10 ;
hence (Ex ((u 'imp' a),PA,G)) . z = TRUE by A1, BVFUNC_1:def 17; :: thesis: verum

end;

case (Ex (a,PA,G)) . z = TRUE ; :: thesis: (Ex ((u 'imp' a),PA,G)) . z = TRUE

then consider x1 being Element of Y such that
A5: x1 in EqClass (z,(CompF (PA,G))) and
A6: a . x1 = TRUE by BVFUNC_1:def 17;
(u 'imp' a) . x1 = ('not' (u . x1)) 'or' (a . x1) by BVFUNC_1:def 8
.= TRUE by A6, BINARITH:10 ;
hence (Ex ((u 'imp' a),PA,G)) . z = TRUE by A5, BVFUNC_1:def 17; :: thesis: verum

end;

end;

end;

hence (Ex ((u 'imp' a),PA,G)) . z = TRUE ; :: thesis: verum