LICORICE by Abby Frucht (Graywolf Press: $18.95; 256 pp.). OK, send your sense of logic out for the rest of the day and pick up Abby Frucht's latest offering, "Licorice," a novel that has the plot structure of a cone of cotton candy and a cast of characters that is either right straight out of "The Twilight Zone" or has overdosed, sure enough, on licorice--the extract for which Liz, our protagonist, has a strong addiction. The first problem with "Licorice" is that we have to cope with a story that is told in the first-person, present tense, a literary technique that has all the natural grace of log-rolling. The second problem with "Licorice," alas, is the story, itself (speaking of log-rolling), which has Liz, a fill-in letter carrier, moving languidly around a small, unidentified town which--for reasons that are never explained or even draped with a hint or two--is inexorably losing its population. Stores close, radio stations go silent, the newspaper folds and we are left with the nagging feeling that this is supposed to be somehow significant. Or maybe, it isn't.