reserve A,B,C for Ordinal,
  X,X1,Y,Y1,Z for set,a,b,b1,b2,x,y,z for object,
  R for Relation,
  f,g,h for Function,
  k,m,n for Nat;
reserve M,N for Cardinal;
reserve S for Sequence;

theorem Th29:
 for x being object holds card { x } = 1
proof let x be object;
A1: 1 = succ 0;
  1 is cardinal
  proof
    take IT = 1;
    thus 1 = IT;
    let A;
    assume A,IT are_equipotent;
    then ex y being object st A = { y } by A1,Th27;
    hence thesis by A1,ZFMISC_1:33;
  end;
  then reconsider M = 1 as Cardinal;
  { x },M are_equipotent by A1,Th27;
  hence thesis by Def2;
end;
