reserve T, X, Y for Subset of MC-wff;
reserve p, q, r, s for Element of MC-wff;

theorem Th32:
  s => (q => p) in IPC-Taut & q in IPC-Taut implies s => p in IPC-Taut
proof
  assume that
A1: s => (q => p) in IPC-Taut and
A2: q in IPC-Taut;
  (s => (q => p)) => (q => (s => p)) in IPC-Taut by Th29;
  then q => (s => p) in IPC-Taut by A1,Def14;
  hence thesis by A2,Def14;
end;
