The Merge Conspiracy [Part 3]

Part 2 and a half showed us the consequences of the MSO-Merge correspondence, both good and bad. In an ideal world, there should be a way to curtail the bad without limiting the good. Alas, ever since J.J. Abrams got his hands on Star Trek I have been uncertain about the degree of idealness of the world we inhabit.

The Merge Conspiracy [Part 2.5]

Yesterday we learned that a constraint can be expressed by Merge iff it can be defined in monadic second-order logic. But is this a good thing or a bad thing? The answer is both.