A crochet hat with hyperbolic frills.

The hats in the HyperHat Collection are all named in honour of famous women mathematicians. This crochet hat is for Sofia Kovalevskaya (1850-1891). All of the hats incorporate an element of hyperbolic knitting or crochet as pioneered by Daina Taimina.

The pattern includes ideas for several variations.

Patterns are available individually or as a collection of six, including three knit and three crochet hats.

See the collection here