RT Journal Article T1 On a general approach to extinction and blow-up for quasi-linear heat equations A1 Velázquez, J.J. L. A1 Galaktionov, V. A. A1 Posashkov, S. A. A1 Herrero, Miguel A. AB The authors study asymptotic behaviour of positive solutions of equations of the type ut =Δφ(u)±Q(u), where φ′ and Q are given positive functions. By determining an auxiliary function F(u) appearing in an expression posed by A. Friedman and B. McLeod, they obtain asymptotic estimates of solutions as t→T, blow-up or extinction time. These estimates have been established by other authors using different methods. Moreover, the paper poses a conjecture that, if the behaviour of u(0,t) as t→T near a blow-up or extinction point is known, all the information about the corresponding asymptotic expansions on small compact subsets near the origin is encoded in the first order ODE φ′(u)ur+rF(u)=0 for r>0 as t→T, where an optimal choice of F(u) is indicated in the paper. PB Pergamon-Elsevier Science SN 0965-5425 YR 1993 FD 1993 LK https://hdl.handle.net/20.500.14352/57858 UL https://hdl.handle.net/20.500.14352/57858 LA eng DS Docta Complutense RD 9 abr 2025