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

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

let a, u be Function of Y,BOOLEAN; :: thesis: for PA being a_partition of Y st u is_independent_of PA,G holds
All ((a 'or' u),PA,G) '<' (Ex (a,PA,G)) 'or' u

let PA be a_partition of Y; :: thesis: ( u is_independent_of PA,G implies All ((a 'or' u),PA,G) '<' (Ex (a,PA,G)) 'or' u )
assume A1: u is_independent_of PA,G ; :: thesis: All ((a 'or' u),PA,G) '<' (Ex (a,PA,G)) 'or' u
let z be Element of Y; :: according to BVFUNC_1:def 12 :: thesis: ( not (All ((a 'or' u),PA,G)) . z = TRUE or ((Ex (a,PA,G)) 'or' u) . z = TRUE )
assume A2: (All ((a 'or' u),PA,G)) . z = TRUE ; :: thesis: ((Ex (a,PA,G)) 'or' u) . z = TRUE
A3: for x being Element of Y holds
( not x in EqClass (z,(CompF (PA,G))) or a . x = TRUE or u . x = TRUE )
proof
let x be Element of Y; :: thesis: ( not x in EqClass (z,(CompF (PA,G))) or a . x = TRUE or u . x = TRUE )
assume x in EqClass (z,(CompF (PA,G))) ; :: thesis: ( a . x = TRUE or u . x = TRUE )
then (a 'or' u) . x = TRUE by ;
then A4: (a . x) 'or' (u . x) = TRUE by BVFUNC_1:def 4;
( u . x = TRUE or u . x = FALSE ) by XBOOLEAN:def 3;
hence ( a . x = TRUE or u . x = TRUE ) by ; :: thesis: verum
end;
A5: ((Ex (a,PA,G)) 'or' u) . z = ((Ex (a,PA,G)) . z) 'or' (u . z) by BVFUNC_1:def 4;
per cases ( for x being Element of Y st x in EqClass (z,(CompF (PA,G))) holds
u . x = TRUE or ( ex x being Element of Y st
( x in EqClass (z,(CompF (PA,G))) & not u . x = TRUE ) & ex x being Element of Y st
( x in EqClass (z,(CompF (PA,G))) & a . x = TRUE ) ) or ( ex x being Element of Y st
( x in EqClass (z,(CompF (PA,G))) & not u . x = TRUE ) & ( for x being Element of Y holds
( not x in EqClass (z,(CompF (PA,G))) or not a . x = TRUE ) ) ) )
;
suppose for x being Element of Y st x in EqClass (z,(CompF (PA,G))) holds
u . x = TRUE ; :: thesis: ((Ex (a,PA,G)) 'or' u) . z = TRUE
then ((Ex (a,PA,G)) 'or' u) . z = ((Ex (a,PA,G)) . z) 'or' TRUE by
.= TRUE by BINARITH:10 ;
hence ((Ex (a,PA,G)) 'or' u) . z = TRUE ; :: thesis: verum
end;
suppose ( ex x being Element of Y st
( x in EqClass (z,(CompF (PA,G))) & not u . x = TRUE ) & ex x being Element of Y st
( x in EqClass (z,(CompF (PA,G))) & a . x = TRUE ) ) ; :: thesis: ((Ex (a,PA,G)) 'or' u) . z = TRUE
then ((Ex (a,PA,G)) 'or' u) . z = TRUE 'or' (u . z) by
.= TRUE by BINARITH:10 ;
hence ((Ex (a,PA,G)) 'or' u) . z = TRUE ; :: thesis: verum
end;
suppose A6: ( ex x being Element of Y st
( x in EqClass (z,(CompF (PA,G))) & not u . x = TRUE ) & ( for x being Element of Y holds
( not x in EqClass (z,(CompF (PA,G))) or not a . x = TRUE ) ) ) ; :: thesis: ((Ex (a,PA,G)) 'or' u) . z = TRUE
A7: z in EqClass (z,(CompF (PA,G))) by EQREL_1:def 6;
A8: a . z <> TRUE by ;
consider x1 being Element of Y such that
A9: x1 in EqClass (z,(CompF (PA,G))) and
A10: u . x1 <> TRUE by A6;
u . x1 = u . z by ;
hence ((Ex (a,PA,G)) 'or' u) . z = TRUE by ; :: thesis: verum
end;
end;