let Y be non empty set ; :: thesis: for G being Subset of (PARTITIONS Y)
for a being Function of Y,BOOLEAN
for PA being a_partition of Y holds a '<' Ex (a,PA,G)
let G be Subset of (PARTITIONS Y); :: thesis: for a being Function of Y,BOOLEAN
for PA being a_partition of Y holds a '<' Ex (a,PA,G)
let a be Function of Y,BOOLEAN; :: thesis: for PA being a_partition of Y holds a '<' Ex (a,PA,G)
let PA be a_partition of Y; :: thesis: a '<' Ex (a,PA,G)
let z be Element of Y; :: according to BVFUNC_1:def 12 :: thesis: ( not a . z = TRUE or (Ex (a,PA,G)) . z = TRUE )
A1: z in EqClass (z,(CompF (PA,G))) by EQREL_1:def 6;
assume a . z = TRUE ; :: thesis: (Ex (a,PA,G)) . z = TRUE
hence (Ex (a,PA,G)) . z = TRUE by A1, BVFUNC_1:def 17; :: thesis: verum