[red75prime]

Sure, we can write a procedure that recognizes some formal grammar, which intersects with the natural language. Defining the formal grammar that fully captures the current natural language understanding of the mathematical community is a bit harder.

[wizzwizz4]

This problem was even worse: it's matched by the formal grammar, but the naïve formalisation has a trivial answer, so it is clearly not what was intended.

[NetMageSCW]

That clearly may be doing some heavy lifting. It is assumed that trivial answer wasn’t what was intended for the problem, but unless someone asked Erdos, I don’t think we know.

[wizzwizz4]

Considering that he did some work towards the problem, tackling non-trivial cases, I think we do know. There's no way he wouldn't have perceived trivial solutions at some point.