for X being Subset of LTLB_WFF
for f, f2 being FinSequence of LTLB_WFF
for i, n being Nat st n + (len f) <= len f2 & ( for k being Nat st 1 <= k & k <= len f holds
f . k = f2 . (k + n) ) & 1 <= i & i <= len f & prc f,X,i holds
prc f2,X,i + n