To most of its citizens and almost all its visitors, Los Angeles is a mystery.

It is huge, amorphous, complicated sometimes frightening and generally incomprehensible.

Like any good mystery, Los Angeles is hard to solve. And like any good mystery, it is worth solving.

Once understood, the city's 463.9 square miles reveal a wealth of answers for anyone seeking beauty, excitement, novelty, frenzy, entertainment, kinkiness, exercise, cheap thrills, expensive thrills and intellectual stimulation. But most people never find them

The American Institute of Architects' Los Angeles chapter, long known to the general public for approximately nothing, plans to come out of its shell with an exhibition that at least partially will solve Los Angeles for its citizens and visitors.

Initiated by the AIA chapter's new executive director, Deborah A. Feldman, the exhibit is scheduled to open early in 1981 and to tell the public about Los Angeles in understandable terms for a change.

To achieve that ambitious goal, Feldman has set out to raise $150,000. And she has enlisted the aid of Richard Saul Wurman (subject to final approval from her AIA chapter directors) who will develop "overall standards" for the exhibition.

Whatever "overall standards" mean, if they involve as significant a part of the exhibit as they appear to, we are in for something of an event.