let Y be non empty set ; :: thesis: for G being Subset of ()
for a, b being Function of Y,BOOLEAN
for PA being a_partition of Y holds (Ex (a,PA,G)) 'imp' (Ex (b,PA,G)) '<' (All (a,PA,G)) 'imp' (Ex (b,PA,G))

let G be Subset of (); :: thesis: for a, b being Function of Y,BOOLEAN
for PA being a_partition of Y holds (Ex (a,PA,G)) 'imp' (Ex (b,PA,G)) '<' (All (a,PA,G)) 'imp' (Ex (b,PA,G))

let a, b be Function of Y,BOOLEAN; :: thesis: for PA being a_partition of Y holds (Ex (a,PA,G)) 'imp' (Ex (b,PA,G)) '<' (All (a,PA,G)) 'imp' (Ex (b,PA,G))
let PA be a_partition of Y; :: thesis: (Ex (a,PA,G)) 'imp' (Ex (b,PA,G)) '<' (All (a,PA,G)) 'imp' (Ex (b,PA,G))
A1: Ex (a,PA,G) = B_SUP (a,(CompF (PA,G))) by BVFUNC_2:def 10;
let z be Element of Y; :: according to BVFUNC_1:def 12 :: thesis: ( not ((Ex (a,PA,G)) 'imp' (Ex (b,PA,G))) . z = TRUE or ((All (a,PA,G)) 'imp' (Ex (b,PA,G))) . z = TRUE )
A2: ( 'not' ((Ex (a,PA,G)) . z) = TRUE or 'not' ((Ex (a,PA,G)) . z) = FALSE ) by XBOOLEAN:def 3;
assume ((Ex (a,PA,G)) 'imp' (Ex (b,PA,G))) . z = TRUE ; :: thesis: ((All (a,PA,G)) 'imp' (Ex (b,PA,G))) . z = TRUE
then A3: ('not' ((Ex (a,PA,G)) . z)) 'or' ((Ex (b,PA,G)) . z) = TRUE by BVFUNC_1:def 8;
A4: z in EqClass (z,(CompF (PA,G))) by EQREL_1:def 6;
per cases ( 'not' ((Ex (a,PA,G)) . z) = TRUE or (Ex (b,PA,G)) . z = TRUE ) by ;
suppose 'not' ((Ex (a,PA,G)) . z) = TRUE ; :: thesis: ((All (a,PA,G)) 'imp' (Ex (b,PA,G))) . z = TRUE
then (Ex (a,PA,G)) . z = FALSE by MARGREL1:11;
then a . z <> TRUE by ;
then (B_INF (a,(CompF (PA,G)))) . z = FALSE by ;
then (All (a,PA,G)) . z = FALSE by BVFUNC_2:def 9;
hence ((All (a,PA,G)) 'imp' (Ex (b,PA,G))) . z = () 'or' ((Ex (b,PA,G)) . z) by BVFUNC_1:def 8
.= TRUE 'or' ((Ex (b,PA,G)) . z) by MARGREL1:11
.= TRUE by BINARITH:10 ;
:: thesis: verum
end;
suppose (Ex (b,PA,G)) . z = TRUE ; :: thesis: ((All (a,PA,G)) 'imp' (Ex (b,PA,G))) . z = TRUE
hence ((All (a,PA,G)) 'imp' (Ex (b,PA,G))) . z = ('not' ((All (a,PA,G)) . z)) 'or' TRUE by BVFUNC_1:def 8
.= TRUE by BINARITH:10 ;
:: thesis: verum
end;
end;