Specializations: Old Church Slavonic; historical and comparative Slavic philology; South Slavic languages, Polish, Russian and Belarusian, the Balkan language area, Old Church Slavonic, Slavic historical grammar, comparative and contrastive grammar, and pedagogical grammar. In general linguistics: syntax, morphology, and phonology (in particular relative and other subordinate clauses) interrogatives, clitic rules, word order, reflexive verbs, accent rules, etc., usually using Slavic material.
Specializations: Syntactic structures of the Germanic languages (especially the older ones) and the Celtic languages (primarily Welsh and Scottish Gaelic), and what they can tell us about the principles of syntactic organization operating in natural language. Germanic philology (Old Norse and Icelandic, Old and Middle High German, Old English, Old Saxon, Gothic, modern German and Scandinavian languages), Celtic language and philology (especially medieval and modern Welsh).
Specializations: Old and Middle English literature; Old Norse-Icelandic literature; English philology. Though primarily interested in literature, he has occasionally served on committees of students interested in linguistics.
Specializations: Indo-European linguistics, Old Irish.