reserve i,j,k,x for object;

theorem Th17:
  EnsCat {0} is pseudo-discrete 1-element
proof
A1: the carrier of EnsCat {0} = {0} by Def14;
  hereby
    let i be Object of EnsCat {0};
    i = 0 by A1,TARSKI:def 1;
    hence <^i,i^> is trivial by Def14,FUNCT_2:127;
  end;
  thus the carrier of EnsCat {0} is 1-element by A1;
end;
