# Veronika Irvine

Bobbin lace is a fibre art form in which intricate and delicate patterns are created by braiding together many threads. When I first learned to make bobbin lace, some 20 years ago, I was struck by its mathematical nature. The patterns are diagrams, not a linear set of instructions. The order in which braids are worked and most of the decisions about how threads should move so that they arrive in the correct position as needed, are left up to the lacemaker. Over the past 4 years, I have been developing a mathematical model for bobbin lace and discovering the joy of designing my own pieces. This process has opened my eyes to more interesting mathematical properties of this art form and allowed me to explore the medium in new ways.

Periodic bobbin lace patterns can be described by a mathematical model. Key elements of the model are 1) a toroidal embedding of a directed graph describing the movement of pairs of threads and 2) a function that maps each vertex of the digraph to a braid word. Using an intelligent combinatorial search, over 100,000 patterns matching the fundamental properties of this model were found. Of these, three closely related patterns were chosen (see inset). The three patterns can be transformed into one another by a small number of changes. The submitted piece was designed to show a gradual transition from one pattern to the next resembling the transformation from perfect, large snowflakes to the slanted, driving snow of a blizzard.