摘要: 1. Introduction. This paper is concerned with a Stefan free boundary problem in which the free boundaries may intersect. Physically it can be thought of as describing a one-dimensional system consisting of a piece of ice immersed in water. Depending on the initial conditions, the piece of ice can melt or the water can freeze at each ice-water interface. In particular the ice can, at some finite time T, melt away entirely.Mathematically, the problem is formulated as follows: Given the data ₁, 42, 43, b₁ and b₂, find six functions s; s (t), j= 1, 2, and u,= u (x, t), i== 1, 2, 3, 4, such that the 6-tuple (S1, S2, U1, U2, uз, u₁) satisfies