Is it possible to switch the current goal or subgoal to prove in Coq?
For example, I have a goal like this (from an eexists):
______________________________________(1/1)
?s > 0 /\ r1 * (r1 + s1) + ?s = r3 * (r3 + s2)
What I want to do is to split and prove the right conjunct first. This I think will give the value of the existential variable ?s, and the left conjunct should be just a simplification away.
But split by default set the left conjunct ?s > 0 as the current goal.
______________________________________(1/2)
?s > 0
______________________________________(2/2)
r1 * (r1 + s1) + ?s = r3 * (r3 + s2)
I know I can prefix tactics with 2: to operate on the second subgoal, but it's awkward because
1) I can't see the hypotheses for goal#2 and
2) if it's in a different context, goal#2 might be the third or the k_th goal. The proof won't be portable.
That's why I want to set the second goal as the current.
BTW, I am using CoqIDE (8.5).
You can use Focus 2 to focus on the second goal.