2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/53650An infinite number of topological conformal algebras with varying central charges are explicitly shown to be present in $2d$ gravity (treated both in the conformal gauge and in the light-cone gauge) coupled to minimal matter. The central charges of the underlying $N=2$ theory in two different gauge choices are generically found to be different. The physical states in these theories are briefly discussed in the light of the $N=2$ superconformal symmetry.Plain Tex, 7 Pages, IC/93/307, (Talk given at the workshop of the ICTP Summer School on String Theory and Related Topics, July, 1993)High Energy Physics - Theorytext