:: Certain Facts about Families of Subsets of Many Sorted Sets :: by Artur Korni{\l}owicz :: :: Received October 27, 1995 :: Copyright (c) 1995-2021 Association of Mizar Users
ex F being ManySortedFunction of F2(),F3() st for i being object st i in F1() holds ex f being Function of (F2() . i),(F3() . i) st ( f = F . i & ( for x being object st x in F2() . i holds P1[f . x,x,i] ) )
provided
A1:
for i being object st i in F1() holds for x being object st x in F2() . i holds ex y being object st ( y in F3() . i & P1[y,x,i] )