
theorem Th29:
  for A being non empty AltGraph, o being Object of A holds (id A).o = o
proof
  let A be non empty AltGraph, o be Object of A;
A1: [o,o] in [:the carrier of A,the carrier of A:] by ZFMISC_1:87;
  thus (id A).o = ((id[:the carrier of A,the carrier of A:]).[o,o])`1 by Def29
    .= ([o,o])`1 by A1,FUNCT_1:18
    .= o;
end;
