Using event sets to concisely represent multiple formula instances

[bestchai]

Given a set of formula instances like this:

• G(a -> XF(b))
• G(a -> XF(c))
• G(d -> XF(b))
• G(d -> XF(c))

We can more concisely represent this set as:

• G({a,d} -> XF({b,c}))

This task involves designing and implementing the above process, in which sets of formula instances are coalesced using sets of event types, as a post-processing step (should only impact the output).

Note that this is trending towards an InvariMint-style representation in which variables in formulas may denote events (lowercase var names), or sets of events (upper-case var names): G(x -> XF(y)) versus G(X -> XF(Y))

[Issue created by bestchai: 2014-08-19]