Specification, equation and agreement in copular sentences

This article presents new data from a number of Germanic languages concerning the agreement patterns found in copular clauses that contain two nominals; both clauses with specificational readings (such as The problem is your parents) and those with what are here termed readings of assumed identity (such as If I were you or In my dream I was you). It is argued that the specificational sentences involve asymmetric equative structures where one nominal is interpreted as in a concealed question, and that the crosslinguistic differences in agreement patterns found in the languages considered follow from the copula lexicalizing either Tense or a lower head.