Conclusion
-1.
(i!1
/=
0)
OR
(j!1
/=
0)
-2.
divides(kk!1,
i!1)
-3.
divides(kk!1,
j!1)
1.
kk!1
<
=
gcd(i!1,
j!1)
Tactic
EXPAND
"gcd"
Premise 1.   (has proof of 9 steps)
-1.
(i!1
/=
0)
OR
(j!1
/=
0)
-2.
divides(kk!1,
i!1)
-3.
divides(kk!1,
j!1)
1.
kk!1
<
=
max({k:posnat
|
divides(k,
i!1)
AND
divides(k,
j!1)})