Much as I enjoyed the unprecedented run of themed group shows at Fleisher/Ollman Gallery over the last few years - and what gallerygoer wouldn't have appreciated a free, first-rate mini-art fair in her or his own city every two months? - it's kind of nice to see the return of the good old-fashioned one- and two-person exhibition.

And it's especially pleasant to have an unimpeded, undistracted view of new work by Bruce Pollock, whose paintings of complex, all-over patterns not only warrant a close look individually, but, displayed together, also create an almost-audible hum of energy as well. For relatively small works, they fill up this large gallery with surprising ease.

In one sense, Pollock's paintings represent a two-dimensional distillation and multiplication of the sculptures he made in the early 1980s, simple, houselike constructions with beautifully painted surfaces. They employ some of the same geometry (albeit a miniaturized version) and sublime coloration as the sculptures. But you could also argue just the opposite - that the fractals of minuscule patterns in his paintings appear to inhabit a vast, uncontained, infinite space.

Nothing is what it initially seems to be in Pollock's paintings. You might assume that six square paintings, each an exploration of a single color using several shades of several hues of the same family and comprising mostly circular forms, would share some other organizing principle. They do not. Pollock's imagery, suggestive of multiple mandalas, nuclei, or wildflowers in a field, seems to have multiplied organically, even with impunity. Look carefully, and you'll see that some of those tinier circles have squeezed their way into these compositions like last-minute subway passengers.

Another series of paintings on rectangular canvases also gives a first impression of having undergone some preliminary plotting and design. But when you study Pollock's Cube Net, for example, its floating cubes are all different, and it's the painting's palette of pale violet, blue, and gray that makes it appear to be composed of precisely repeated patterns.

Pollock's tour-de-force is an ink-and-pencil drawing on an 8-inch-wide, 20-foot-long scroll of white paper, in which patterns of aggregations of rectangles give way to honeycomblike formations, which give way to multiple circles, and so on - produced, one imagines, like the surrealist game Exquisite Corpse played by one. It looks like sheet music and an aerial map of a city combined, and it's clearly a Baedeker to Pollock's micro/macro worlds.

Fleisher/Ollman Gallery, 1616 Walnut St., 10:30 a.m. to 5:30 p.m. Mondays through Fridays, 12 to 5 p.m. Saturdays. 215-545-7562 or Through May 9.

Felis sapiens

Cats aren't just cats in Yuichi Hibi's photographs; they're people. (That is what cat lovers have always maintained, of course, but even dog people will find these images convincing.)

Hibi, an actor and filmmaker-turned-photographer known for his black-and-white images that portray the urban night as a stage for sinister doings, has projected a similar sense of mystery and potential menace onto homeless cats.

In Hibi's pictures, these cats could be stars of a film noir, slinking along alleys and giving the photographer a defiant backward glance. Cartier-Bresson's photographs of self-possessed French prostitutes come to mind occasionally, as do some of Bill Brandt's dark, confrontational portraits of postwar Britons. And yet, Hibi also has captured a poignance in the lives of his subjects that provokes a profound empathy. Even in those who are unequivocably dog people.

Gallery 339, 339 S. 21st St., 10 a.m. to 6 p.m. Tuesdays through Saturdays. 215-731-1530 or Through May 16.