Theory of heat equations for sigma functions

Let e and q be fixed co-prime integers satisfying 1 < e <q. Let C be a certain family of deformations of the curve ye =xq. That family is called the (e, q)-curve and is one of the types of curves called plane telescopic curves. Let Δ be the discriminant of C. Following pioneering work by Buchstaber and Leykin (BL), we determine the canonical basis {Lj} of the space of derivations tangent to the variety Δ=0 and describe their specific properties. Such a set {Lj} gives rise to a system of linear partial differential equations (heat equations) satisfied by the function σ(u) associated with C, and eventually gives its explicit power series expansion. This is a natural generalisation of Weierstrass' result on his sigma function.We attempt to give an accessible description of various aspects of the BL theory. Especially, the text contains detailed proofs for several useful formulae and known facts since we know of no works which include their proofs.