Channa Horwitz produced a large body of works which she derived from mathematical equations and equivalences. She took simple sets of numbers and applied different operations to them to produce varied convolutions, which she then expressed as graphic marks, spoken words, or gestures. Individually, the geometries that emerge from these processes—whether drawn, voiced, or danced—might be redolent of a Charles Rennie Mackintosh frieze, the whispering of a stand of birches in autumn light, or the texture of gingham. Whatever they may become, the pieces always evince a scrupulous commitment to the unfolding of a defined arithmetic. Unlike certain other American artists of her generation who explored serial techniques, systems, and numerical progressions—Lucinda Childs, Christian Wolff, and her friend Sol LeWitt—Horwitz gained little recognition until the last years of her life. She passed, aged 80, in 2013. Nigel Prince, director of Vancouver’s Contemporary Art Gallery (CAG), has worked closely with Ellen Davis (Horwitz’s daughter, who manages her mother’s estate) to curate an intimately scaled exhibition that does more than simply outline the themes of her intellectual biography or harvest a series of visual highlights. The exhibition collates a satisfying and provocative range of materials which include drawings, performance scores, archival documentation, and …