reserve A,B,C,Y,x,y,z for set, U, D for non empty set,
X for non empty Subset of D, d,d1,d2 for Element of D;
reserve P,Q,R for Relation, g for Function, p,q for FinSequence;
reserve f for BinOp of D, i,m,n for Nat;

theorem Th6: for p being FinSequence st p is U-valued & p is non empty
holds U-firstChar.p=p.1
proof
let p be FinSequence; assume p is U-valued & p is non empty; then
reconsider pp=p as non empty FinSequence of U by Lm1;
U-firstChar.pp=pp.1 by Lm22; hence thesis;
end;
