Three original works of science fiction, a ""novelet"" and two novellas--though what makes Bishop's ""Cold War Orphans"" a novelet and Malzberg's equally brief ""Le Croix (The Cross)"" a novella is hard to say. McAllister, a well-known sf editor and sometime' story-writer, contributes ""Their Immortal Hearts,"" in which a young underground freedom-fighter undertakes an elaborate impersonation designed to liberate her planet from the wealthy immortal who has controlled its wealth for 250 years. A slew of modish computer-graphics cannot disguise the conventionality of the material, though there are some ingenious details. The Malzberg story is a witty exploration of psychological time-travel a little analogous to Chorale (1978); a weary anomic seeking computerized fantasy-thrills finds his re-enactments of various religious martyrdoms becoming a real defiance of the real oppression represented by his own blandly benevolent world. ""Cold War Orphans,"" written with Bishop's customary economy and verve, also involves martyrdom of a sort, this time on the part of a U-2 pilot who devises a one-way route out of the world he has been making safe for democracy. (As often happens with Bishop, one suspects that a fine story would have been still better without the grandiose framework of allusions he has lavished on it.) A pleasant threesome.