Galerie Lahumière’s new show, Approaches to Color, features four artists of differing generations: Gottfried Honegger (1917–2016), Hans-Jörg Glattfelder (1939–), Sigurd Rompza (1945–) and Nicholas Bodde (1962–). All live in Germany or Switzerland, and all practice a rational, geometric abstraction also known as art concret.