TY - GEN A1 - Stephani, Hans A1 - Wolf, Thomas T1 - Spherically symmetric perfect fluids in shearfree motion - the symmetry approach N2 - In General Relativity, the motion of expanding shearfree perfect fluids is governed by the ordinary differential equation $y^{\prime \prime }=$ $% F(x)\,y^2$ , where $F$ is an arbitrary function from which the equation of state can be computed. A complete symmetry analysis of this differential equation is given; its solutions are classified according to this scheme, and in particular the relation to Wyman's Painlev\'e analysis is clarified. T3 - ZIB-Report - SC-96-14 Y1 - 1996 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-2253 ER -