I'd appreciate help with this sentence:
Let there be a language L and a structure M, and I need to prove the following sentence is logically false: $$\varphi :\exists xR(x)\rightarrow \forall yR(y)$$
My problem with this is that I'm having a hard time understanding what an unary relation is. The same example would be much easier (for me) if R was a binary relation.
I'd appreciate some examples for such a relation. Thank you