reserve o,m for set;
reserve C for Cartesian_category;
reserve a,b,c,d,e,s for Object of C;

theorem
  (a[x]b)[x]c,a[x](b[x]c) are_isomorphic
proof
  thus Hom((a[x]b)[x]c,a[x](b[x]c)) <> {} & Hom(a[x](b[x]c),(a[x]b)[x]c) <> {}
  by Th36;
  take Alpha(a,b,c), Alpha'(a,b,c);
  thus thesis by Th37;
end;
