Conclusion
-1.
(i!1
/=
0)
OR
(j!1
/=
0)
1.
divides(gcd(i!1,
j!1),
i!1)
AND
divides(gcd(i!1,
j!1),
j!1)
Tactic
EXPAND
"gcd"
Premise 1.   (has proof of 8 steps)
-1.
(i!1
/=
0)
OR
(j!1
/=
0)
1.
divides(max({k:posnat
|
divides(k,
i!1)
AND
divides(k,
j!1)}),
i!1)
AND
divides(max({k:posnat
|
divides(k,
i!1)
AND
divides(k,
j!1)}),
j!1)