# Bridges 2010 Regular Paper

Strip Symmetry Groups of African Sona Designs

Darrah Chavey

(Proceedings pages 111–118)

## Abstract

The sona drawings of the Chokwe people of Angola/Congo are continuous
one-line drawings, generally made in the sand, that are often used
to build highly symmetric one-line drawings. A large class of these
drawings can be viewed as a form of “mirror curves,” visualizable
as a curve bouncing through an arrangement of dots, bouncing off
“mirrors” placed between some of the dots, and leaving a symmetric,
closed trail behind. To investigate some of the possibilities for
such Chokwe sona, we construct such sona for all 7 strip symmetry
groups on all but the smallest rectangles. This allows us to use
mathematical techniques to build classes of sona that, we argue,
meet the artistic goals of the Chokwe people, and (we hope) would
be viewed favorably by the historic artists of this culture.

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