Combining sets with cardinals
We introduce a quantifier-free set-theoretic language for combining sets with elements in the presence of the cardinality operator. We prove that the language is decidable by providing a combination method specifically tailored to the combination domain of sets, cardinal numbers, and elements. Our method uses as black boxes a decision procedure for the elements and a decision procedure for cardinal numbers. To be correct, our method requires that the theory of elements be stably infinite. However, we show that if we restrict set variables to range over finite sets only, then one can modify our method so that it works even when the theory of the elements is not stably infinite.
combining sets cardinality set-theoretic language decision procedure