reserve k,m,n for Element of NAT,
  i, j for Nat,
  a, b, c for object,
  X, Y, Z for set,
  D, D1, D2 for non empty set;
reserve p, q, r, s for FinSequence;
reserve t, u, v, w for GRZ-formula;
reserve R, R1, R2 for GRZ-rule;
reserve A, A1, A2 for non empty Subset of GRZ-formula-set;
reserve B, B1, B2 for Subset of GRZ-formula-set;
reserve P, P1, P2 for GRZ-formula-sequence;
reserve S, S1, S2 for GRZ-formula-finset;

theorem Th75:
  for t holds t '=' t is LD-provable
proof
  let t;
  set u = t '&' t;
  A2: t '=' u is LD-provable;
  then u '=' t is LD-provable by Th70, XBOOLE_1:7;
  hence thesis by A2, Th74;
end;
