Conclusion
-1.
add(choose(vert(G!1)),
union(r1(G!1),
r2(G!1)))
=
vert(G!1)
1.
(card(r1(G!1))
+
card(r2(G!1)))
>
=
(card[T](vert(G!1))
-
1)
Tactic
REPLACE
"-1"
*
RL
Premise 1.   (has proof of 5 steps)
-1.
add(choose(vert(G!1)),
union(r1(G!1),
r2(G!1)))
=
vert(G!1)
1.
(card(r1(G!1))
+
card(r2(G!1)))
>
=
(card[T](add(choose(vert(G!1)),
union(r1(G!1),
r2(G!1))))
-
1)