ACTING is an if-then proposition. To create a character an actor asks, "If I am Hamlet and I discover that my uncle killed my father, then how will I react?" Unfortunately, the actors and director at Leverett House do not use sufficient imagination and, understandably, have not known enough of life to make Michel de Ghelderode's A Night of Pity palatable.

The play, which is full of life's nothingness, despair, and death, manufactures miserable versions of characters from mythology. It could succeed; its Bacchus as a barkeep who can't get drunk and a psychotic slattern who might be an uglified and twisted Aphrodite are curious figures, and a raid by a masked group led by Death always has dramatic potential.

But last night's masked horrors looked and behaved like a bunch of kids out for trick-and-treat. Patricia Smith's slattern recalled a hoarse and unhappy spinster. And like the other actors, Bacchus (Michael Cline) relied on pronouncing lines in a pseudo-theatrical voice.

Most painful, Director Jack Viertel stretched the eighteen minute playlet to half an hour, on the theory that unhappiness slows all conversations down to 121/2 rpm. He mis-paced differently in the mask scene, which moved too fast to contain the action and the full cast.

The Dollar Theater people came closer to success with William Saroyan's melodramatic Hello Out There. Apparently a Texas jailhouse is easier to relate to than the Flemish de Ghelderode's fantasies.

Ken Hurwitz, with energy and boyish sex appeal, played The Young Gambler framed for raping a pick-up, whose request for money he had refused. However, Marcie Kaplan was too pretty to understand the lonely jail maid who thinks herself ugly and falls in love with Hurwitz. She resorts to cliched gestures of gawkiness and insecurity, like sticking her stomach out.

Saroyan's version of boy meets girl seems sticky, but this production directed by Michael Cline could have given more insights into the characters as three-dimensional people. At least Saroyan makes the point that provincial Texas towns are best gotten out of before sundown.

Steve Flax's set had absolutely no relation to the plays except for a row of jail bars, and even an abstract set should consider the play. The backdrop of overlapping rectangles in a single plane didn't even work as a composition of forms. And Light Designer Udi Gupta shouldn't have left unlit spots on stage as well as shadowing actors' faces, sometimes preferring to light their legs.

A "Dollar Theater " sounds attractive in theory, but as Senator Stephen Young of Ohio sometimes replies to letters from constituents, "I realize your opinion cost nothing, but that's exactly what it's worth."