I have a formula
and an interpretation I:
Where D is the domain, and R1 is the set of relations.
I am trying to prove or disprove that I is a model for A. I believe that it is. However, I am unsure how I would go about proving it. Couldn't any random assortment of two-tuples from the domain be in R1 and this interpretation would still be a model?
Hint: rewrite the part $\lnot A\lor\lnot B\lor C$ of the formula as $(A\land B)\to C$, and draw the given relation $R_1$ (observe that only the numbers $1,2,3,5,8$ are used).