Where would the American dance avant-garde be without the French? Trisha Brown and Lucinda Childs have depended on France for their commissions. French conceptual choreographers have blessed Yvonne Rainer’s gloriously outlandish theories with knotty new life. As for the prolific, fiercely loved dance giant Merce Cunningham, French repertory companies, not the American, have kept his work alive since his death, in 2009, devoting themselves to his precise and impulsive idiom, embodying the work with conviction and understanding. The eclectic Lyon Opera Ballet was an early adapter, first presenting the creaturely 1991 Beach Birds in 2008. This month, the Lyon troupe adds the gorgeous, slippery, ghostly, and apocalyptic late work BIPED. The double bill is entitled “Merce Cunningham Forever.” We sure hope so. —Apollinaire Scherr