Is this predicate logic semantic tree open or closed?

Question

I have this formula: $\forall y\neg A(y)\land\exists x A(x)$ .

Is a semantic tree for this formula closed or open?

The formula is obviously unsatisfiable. – Mauro ALLEGRANZA Jan 26 '20 at 12:06 — Mauro ALLEGRANZA, Jan 26 '20 at 12:06

score 1 · Accepted Answer · answered Jan 26 '20 at 12:15

1

Obviously it is closed.

Just think about the definition of closed formula :

A formula is closed if it does not contains free occurrence.

answered Jan 26 '20 at 12:15

IMO, the question is about the semantic tree and not about the syntax of the formula. – Mauro ALLEGRANZA Jan 26 '20 at 12:37

1 Answers1