On the cotangent cohomology of rational surface singularities with almost reduced fundamental cycle

2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/69600We prove dimension formulas for the cotangent spaces $T^{1}$ and $T^{2}$ for a class of rational surface singularities by calculating a correction term in the general dimension formulas. We get that it is zero if the dual graph of the rational surface singularity $X$ does not contain a particular type of configurations, and this generalizes a result of Theo de Jong stating that the correction term $c(X)$ is zero for rational determinantal surface singularities. In particular our result implies that $c(X)$ is zero for Riemenschneiders quasi-determinantal rational surface singularities, and this also generalise results for qoutient singularities.11 pages, one figureAlgebraic Geometry14B07; 14B10; 13D03On the cotangent cohomology of rational surface singularities with almost reduced fundamental cycletext