Craig interpolation has become a versatile tool in formal
verification, in particular for generating intermediate assertions in
safety analysis and model checking. As a result, the development of
efficient interpolation procedures for expressive logical theories has
received a lot of attention over the last years. I will summarise our
recent work on interpolation procedures, for theories for which
previously no efficient procedures were known: quantifier-free
Presburger Arithmetic, in combination with (i) uninterpreted
predicates (QPA+UP), (ii) uninterpreted functions (QPA+UF) and (iii)
extensional arrays (QPA+AR). Since none of the combined theories
can be effectively interpolated without the use of quantifiers, even if
the input formulae are quantifier-free, I will identify fragments
of QPA+UP and QPA+UF with restricted forms of guarded quantification
that are closed under interpolation.