Inferring descriptive generalisations of formal languages

► We study limit learners that output descriptive patterns instead of exact grammars. ► Inferrability of indexed families depends on concepts related to Angluinʼs telltales. ► Our model is shown to be an instance of a natural extension of Gold-style learning. ► Terminal-free E-descriptive patterns can be inferred for rich classes of languages. ► Our proofs make use of novel insights into combinatorial properties of such patterns.