Like Xenakis, American ex-pat composer Tom Johnson has long been enamored of mathematics, and he’s used the practice as the discipline as an integral tool in his compositional work. These string quartets — played with characteristic precision, brio, and warmth by Montréal’s Quatuor Bozzini — often deploy the theory of combinations, setting out every possible permutation or sequence from a small amount of material. While that concept might sound like an excursion toward boredom, the results are thrilling. Johnson was an early advocate and pioneer of minimalism, and that interest distinguishes these four works, composed between 1994 and 2009, with a mixture of rigor and curiosity that turns to math as a way of translating the patterns and shapes of the world around us into music. Johnson achieves a particularly vivid realization on the concise Tilework for String Quartet, a 10-minute canon that explores the different ways the rhythms in a six-note line can overlap and fit together. Four-Note Chords in Four Voices is a study of the possible combinations delineated in the title, with the composer’s program note explaining that “There are 495 ways to distribute two notes in group,” but there’s nothing schematic or cold in the way Johnson traces out those possibilities anywhere on the album.