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;
