let X, Y be non empty set ; for F being disjoint_valued FinSequence of bool [:X,Y:]
for p being set holds
( ex Fy being disjoint_valued FinSequence of bool X st
( dom F = dom Fy & ( for n being Nat st n in dom Fy holds
Fy . n = Y-section ((F . n),p) ) ) & ex Fx being disjoint_valued FinSequence of bool Y st
( dom F = dom Fx & ( for n being Nat st n in dom Fx holds
Fx . n = X-section ((F . n),p) ) ) )
let F be disjoint_valued FinSequence of bool [:X,Y:]; for p being set holds
( ex Fy being disjoint_valued FinSequence of bool X st
( dom F = dom Fy & ( for n being Nat st n in dom Fy holds
Fy . n = Y-section ((F . n),p) ) ) & ex Fx being disjoint_valued FinSequence of bool Y st
( dom F = dom Fx & ( for n being Nat st n in dom Fx holds
Fx . n = X-section ((F . n),p) ) ) )
let p be set ; ( ex Fy being disjoint_valued FinSequence of bool X st
( dom F = dom Fy & ( for n being Nat st n in dom Fy holds
Fy . n = Y-section ((F . n),p) ) ) & ex Fx being disjoint_valued FinSequence of bool Y st
( dom F = dom Fx & ( for n being Nat st n in dom Fx holds
Fx . n = X-section ((F . n),p) ) ) )
deffunc H1( Nat) -> Subset of X = Y-section ((F . $1),p);
deffunc H2( Nat) -> Subset of Y = X-section ((F . $1),p);
thus
ex Fy being disjoint_valued FinSequence of bool X st
( dom F = dom Fy & ( for n being Nat st n in dom Fy holds
Fy . n = Y-section ((F . n),p) ) )
ex Fx being disjoint_valued FinSequence of bool Y st
( dom F = dom Fx & ( for n being Nat st n in dom Fx holds
Fx . n = X-section ((F . n),p) ) )
thus
ex Fx being disjoint_valued FinSequence of bool Y st
( dom F = dom Fx & ( for n being Nat st n in dom Fx holds
Fx . n = X-section ((F . n),p) ) )
verum