Conclusion
1.
(card(r1(G!1))
+
card(r2(G!1)))
>
=
((((card(r1(G!1))
+
card(r2(G!1)))
-
card(intersection(r1(G!1),
r2(G!1))))
+
IF
union(r1(G!1),
r2(G!1))(choose(vert(G!1)))
THEN
0
ELSE
1
ENDIF)
-
1)
Tactic
LIFT-IF
Premise 1.   (has proof of 1 step)
1.
IF
union(r1(G!1),
r2(G!1))(choose(vert(G!1)))
THEN
(card(r1(G!1))
+
card(r2(G!1)))
>
=
((((card(r1(G!1))
+
card(r2(G!1)))
-
card(intersection(r1(G!1),
r2(G!1))))
+
0)
-
1)
ELSE
(card(r1(G!1))
+
card(r2(G!1)))
>
=
((((card(r1(G!1))
+
card(r2(G!1)))
-
card(intersection(r1(G!1),
r2(G!1))))
+
1)
-
1)
ENDIF