The two artists and long-time collaborators speak to Evan Moffitt about the influence of Fluxus, the importance of improvisation and the challenge of reckoning with art history 

Some questions seem so obvious they are almost never asked. With the proliferation of museums, biennales and fairs, and the sheer amount of work now being made, shown, and sold, the art world has obviously changed substantially over the last 40 or so years. But what have been the most important shifts in art and the structures that surround it? frieze has asked 33 artists, collectors, critics, curators, educators and gallerists to respond