Does $∃x (Px⇔Rx)$ imply $(∃xPx ⇔ ∃xRx)$ ?
I am trying to make an interpretation that verifies $∃x (Px⇔Rx)$ and falsifies $(∃xPx ⇔ ∃xRx).$ I have been trying for a while now, and I don't think it is possible.
On the other hand, I do know that $(∃xPx ⇔ ∃xRx)$ does not imply $∃x (Px⇔Rx).$
$$∃x\:(Px⇔Rx)\tag1$$ means that some object satisfies either both or neither of $P$ and $R.$
$$∃xPx⇔∃xRx\tag2$$ means that $P$ and $R$ are either each satisfied by some object or each satisfied by no object (i.e., $P$ and $R$ are both either empty or nonempty).
The countermodel
shows that $$(1)\kern.6em\not\kern-.6em\implies(2),$$ while the countermodel
shows that $$(2)\kern.6em\not\kern-.6em\implies(1).$$