actualize set-union
with domain
by morphism : set → domains; : elem → domain; ∅ → ∅; ++ → ++; # → #; { } → { }; ∪ → ∪; ∩ → ∩; \ → \; -- → --; ∈ → ∈; ⊆ → ⊆; s → domsvar;
s0 → domsvar0; s1 → domsvar1; s2 → domsvar2; a → domvar; b → domvar0; c → domvar1;
end actualize