reserve x,y,z for set;
reserve f,f1,f2,f3 for FinSequence,
  p,p1,p2,p3 for set,
  i,k for Nat;
reserve D for non empty set,
  p,p1,p2,p3 for Element of D,
  f,f1,f2 for FinSequence of D;

theorem Th88:
  f just_once_values p implies Rev(f-:p) = Rev f :-p
proof
  assume
A1: f just_once_values p;
  then
A2: p in rng f by FINSEQ_4:5;
  then
A3: p in rng Rev f by FINSEQ_5:57;
  thus Rev(f-:p) = Rev((f-|p)^<*p*>) by A2,Th40
    .= <*p*>^Rev(f-|p) by FINSEQ_5:63
    .= <*p*>^(Rev f |-- p) by A1,Th38
    .= Rev f :-p by A3,Th41;
end;
