 One easily checks that all the generalized quantifiers exemplified so far are indeed Isom. We did not include this requirement in the definition of generalized quantifiers however, since there are natural language quantifiers that do not satisfy it; see below. But logic is supposed to be topic-neutral, so Isom is almost always imposed. Then two important things follow. First, as indicated above, sentences in logical languages do not distinguish isomorphic models. More precisely, we have the following