2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/196822We investigate effects of time evolution of a rich cluster of galaxies on its member galactic halos in the standard cold dark matter (SCDM) universe using high resolution N-body simulations. We identify several hundred galactic halos within virial radius of our simulated cluster. We also find that a large number of halos have been tidally disrupted at z = 0. Therefore we improve a method of deriving merging history trees of galaxies taking account of tidally stripped galaxies.20 pages, 14 Postscript figures, uses AASTeX, accepted for publication in ApJAstrophysicstext