[Author] O. I. Reinov [Title] Excursus to the theory of the approximation of operators in operator ideals [AMS Subj-class] 47B10 Hilbert--Schmidt operators, trace class operators, nuclear operators, p-summing operators, etc. [Abstract] A survey on the approximation in the spaces of nuclear operators, of summing operators in different topologies, as well as in spaces of general linear operators in the topology of compact convergence by operators from various classes (e.g., by weakly compact operators). There are many counterexamples to well known problems. [Comments] AmSTeX, 36 pp., Russian [Contact e-mail] orein@orein.usr.pu.ru