Katsumi ISHIKAWA Title: A quandle approach to Hoste's conjecture Abstract: In 2002, Hoste proposed a conjecture based on his computer experiments: the real part of every root of the Alexander polynomial of an alternating knot will be greater than $-1$, which is now called Hoste's conjecture. In this talk, we approach this conjecture by means of quandles. In this viewpoint, Hoste's conjecture is interpreted as the nonexistence of a nontrivial coloring by certain quandles. In particular, we prove Hoste's conjecture for the 2-bridge knots.