for S1 being OrderSortedSign
for U1, U2 being non-empty OSAlgebra of S1
for F being ManySortedFunction of U1,U2 st F is order-sorted holds
for o1, o2 being OperSymbol of S1 st o1 <= o2 holds
for x being Element of Args (o1,U1)
for x1 being Element of Args (o2,U1) st x = x1 holds
F # x = F # x1