Abstract. We solve a restricted version of the Finite Type Problem from natural duality theory: if a finite unary algebra is dualisable, then it is dualisable via a finite set of relations.

AMS Subject Classification (1991): 08C20, 08A60

Keyword(s): natural duality, dualizable, unary algebra, Hanf number for dualizability

Received April 14, 2010, and in final form August 25, 2010. (Registered under 26/2010.)