If ""Arrivals and Departures"" sounds like a blandly all-purpose modern-fiction title, it's an appropriate one for this slim first novel--because Robinson (whose stories have appeared in Redbook and Cosmopolitan) comes across here as a nice enough writer with nothing in particular to write about. Her young, urban heroine is Sophie Jones, a Philadelphia high-school teacher whose live-in lover Tim has just taken off, without warning, for the Coast. So Sophie is left to muse on dependency and mothering, to binge on barbecued potato chips, to try a few blind dates (a slimy type makes heavy passes and, rebuffed, says, ""What are you . . . some kind of lesbian?""). But mostly Sophie's emotional neediness gets channeled into her relationship with her new dog (a stray whom she cutesily calls ""Dog""), about whom her feelings become intensely possessive, even erotic: ""His white buttocks were fluffy, his asshole was a neat slit . . . his prick was a tender ski jump. . . . Oh, he was perfect in every detail, the Platonic ideal of a dog."" And, much more persuasively, Sophie gets involved with her students--especially handsome Joe (about whom she has sex fantasies till he whimperingly asks for help in getting D treatment) and unprepossessing Maria, who dresses unspeakably, doesn't bathe, but might have talent: ""The thing about Maria's poems was that when Sophie read them, she believed Maria would not turn into a shopping bag lady."" The Sophie/ Maria scenes offer the best moments here, but Robinson, short of plot, arbitrarily ends the relationship with sudden death. And, after a semi-affair with an old professor and a brief encounter with a fellow camper, Sophie takes off on a vacation to Greece . . . for a zero of a fadeout. A virtual non-novel, then, despite the usual comic best-friend, texturizing references (to Joan Didion, Lillian Hellman, and Muriel Rukeyser), and tidbits of writer's-notebook wisdom (""People's farts smelled okay to their makers""). But Robinson shows enough low-key wit and basic style to promise better things ahead once she finds some specific, involving subject matter.