=ADD= =reftype= 14 =number= 99-11 =url= ftp://ftp.risc.uni-linz.ac.at/pub/techreports/1999/99-11.ps.gz =year= 1999 =month= 04 =author= Hillgarter; Erik =title= The Classification Problem for (Point) Symmetries of 2nd Order PDE's in one Dependent and two Independent Variables =abstract= This report deals with the most important means for finding closed form solutions of differential equations, namely the so called non-trivial symmetries that a given DE may admit. =note= SFB Report =sponsor= FWF project F013, SFB F013