New works by Murray Schisgal, Stuart Sherman.; Exercise in comic arithmetic -- and an offbeat look at Hamlet; Hamlet (a Portrait) Theater piece created by and featuring Stuart Sherman

Brevity is the soul of Stuart Sherman's art. So it isn't surprising that his show at the Performing Garage includes a tape-recorded ''sound piece,'' four movies, a stand-up routine, and his version of ''Hamlet,'' all in the space of about 35 minutes.

The heart of the evening is ''Hamlet (A Portrait),'' which Sherman has previously presented in Amsterdam and Paris. While it seems complete in itself, it is part of a ''classical trilogy'' that will also include ''Faust'' (already performed in West Germany) and ''Oedipus.''

Sherman is fascinated with the relationships between meanings, objects, and words. His elegant ''Hamlet'' uses Shakespeare as the launching pad for another exploration of this complicated realm. His props are objects representing different degrees of literal and symbolic meaning. For example, the actors wear a series of masks. The first carries the image of a face; the second shows the skull under the face; the third bears a name rather than a picture; the fourth is a stylized outline; the fifth is blank but retains the shape of the other masks. Similar series - moving from literal meaning to stylized outline, with language at the midpoint - are etched on boxes and implements that figure in the action.

Slowly, as if this were a solemn ritual, Sherman and the other performers work through a set of precise maneuvers involving doors, swords, cubes of plastic and cardboard, and the hand-held tape recorders that often figure in his work. The effect is not very Shakespearean - the play is used as a handy icon, not a drama - but rhythmic, engaging, and witty for all that. Idiosyncratic though he is, Sherman clearly knows a hawk from a handsaw.

The program also includes four movies: ''Bridge Film,'' made in France; the rigorous ''Chess''; and two that reflect Sherman's recent switch to sound - ''Racing'' and ''Typewriting (Pertaining to Stefan Brecht).'' Rounding out the evening were the tape-recorded ''Doors,'' an amusing and evocative bit of earplay, and a preview of Sherman's next one-man ''spectacle,'' to be called ''Time.'' It promises to be another pithy and inventive chapter in Sherman's carefully evolving career.