ON STAGE

* The Food Chain

(Westside Theatre): Nicky Silver's dizzying comedy is flat-out funnier than anything else currently around. It ditches the pretensions of his earlier work while still making a point about the extremes that desperate people are willing to go in their search for love.

Silver's version of the food chain is a hilarious delineation of the battle between the sexes performed in three scenes. The first is about a young artist (played by Hope Davis) despondent over her husband's disappearance.

The second segment presents a handsome gay model, (Patrick Fabian), who is visited one night by Otto (Tom McGowan), an ex-companion who is now eating himself into oblivion.

The third segment features all the characters, who come together in an unlikely but hilarious confluence of events.

''The Food Chain'' is given perfect pitch by director Robert Falls.

* Mathis der Maler

(New York City Opera): The ever-adventurous NYCO has done it again, with this presentation of a 1935 opera by Paul Hindesmith that has, unbelievably, never been given a professional American production. Banned by the Nazis because of its references to political tyranny, this work (better known as a symphony) is built around the German Peasants' War of the 16th century. It is based on the life of the religious painter Matthias Grunewald, and is a complicated, cerebral piece with often gorgeous music. It has been given a superb, stark production, with a powerful performance by William Stone in the lead role.

* Standing By

(York Theater Company through Oct. 15): Broadway veteran Norman Barasch (''Make a Million,'' ''Send Me No Flowers'') has written a romantic comedy-drama about the intense affair between a frustrated television writer and a dying flutist. Although the play trods much familiar terrain, at times veering uncomfortably close to ''Love Story,'' it is made palatable by engaging dialogue and the charming performances by Gregg Edelman and Cynthia Watros.