Department of Mathematics, Pomona College, Claremont, CA 91711, USA. jo.hardin@pomona.edu|Department of Mathematics, Pomona College, Claremont, CA 91711, USA. jo.hardin@pomona.edu|Department of Mathematics, Pomona College, Claremont, CA 91711, USA. jo.hardin@pomona.edu|Department of Mathematics, Pomona College, Claremont, CA 91711, USA. jo.hardin@pomona.edu