2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/207055Numerical relativity has faced the problem that standard 3+1 simulations of black hole spacetimes without singularity excision and with singularity avoiding lapse and vanishing shift fail after an evolution time of around 30-40M due to the so-called slice stretching. We discuss lapse and shift conditions for the non-excision case that effectively cure slice stretching and allow run times of 1000M and more.19 pages, 14 figures, REVTeX, Added a missing AcknowledgmentGeneral Relativity and Quantum Cosmologytext