
theorem
  for M being finite-degree Matroid for B1,B2 being Basis of M holds
  card B1 = card B2
proof
  let M be finite-degree Matroid;
  let B1,B2 be Basis of M;
A1: B2 is_maximal_independent_in [#]M by Def12;
  B1 is_maximal_independent_in [#]M by Def12;
  hence thesis by A1,Th16;
end;
