Can the two camps bear the tension when the jazz mainstream meets the avant-garde?

This question was partly answered last night at Carnegie Hall when pianists Mary Lou Williams and Cecil Taylor performed in tandem before 2,800 persons.

At one piano sat Williams, 66, ever-swinging, veteran of the jazz glory days in the Kansas City of the '30s, mother figure to many modern jazz men in the '40s and '50s, and creator of pulsating-hummable melodies.

At the other piano sat Taylor, 44, an enfant terrible for 20 years, conservatory-trained, molder of dissonant harmonies and zig-zag melodies and renegade figure to the mainstreamers.

The concert was titled "Mary Lou Williams Cecil Taylor Embraced." The title was Taylor's and the photograph of the two artists conveyed that feeling.

However, tension boiled between the pianists during the 10 days of rehearsal time. They argued about each other's musical responsibilities and abilities.

Sitting in her apartment in Harlem's Sugar Hill, today only a deteriorating faded shadow of the glistening, fashionable neighborhood it was 40 years ago, Williams said working with Taylor was difficult. "He's nervous and tense," she explained.

Why did she ask him to perform with her? "Because he is creative and honest," she replied.

Taylor said the rehearsals had been tense because Williams wanted him to play her male but refuse to try to perform his music the way he wanted it heard.

"I can play to accompany Mary and get her off," he said, sitting in his loft apartment studio in Lower Manhattan about two blocks from City Hall. "I know what she likes and I know how to construct pieces that will get her off."

Taylor, 5-feet-6, 140 pounds, is a bundle of energy. Some part of his body moves whenever he talks. His shoulders rock, his hands gesticulate, his head bobs or he paces the floor.

"One of the more powerful things about Mary Lou Williams is that she has emotional roots in at least two or three different periods in the development of this music," he said. "If we'd compared that to European music, she has the understanding to write Beethoven's 'Fifth Symphony' as well as Stravinsky's 'Rite of Spring.'"

But apparently she does not take to some aspects of Taylor's music, which has its classical counterparts in Bartok and Schoenberg.

The idea for this concert was Williams. She financed and promoted it - with the help of her friend, Peter O'Brien, a Society of Jesuits priest.

"I didn't want to be bothered with impresarios," she said. "It's costing more than I thought, but I wanted to do it to explore the history of jazz - spirituals, ragtime, Kansas City style, swing. The real jazz has a healing element, a spiritual aspect." [PARAGRAPH ILLEGIBLE]

She converted to Catholicism in 1956 and has used much of her time since for charity work. In the late '50s, she [LINE ILLEGIBLE]

For Williams, who just received her second Greenhelm Fellowship, playing duo piano is not new. She did it in public as far back as the '60s. But probably more interecting were the private sessions she had was pioneer modern jazz, pianists Thaiodious Monic and Bud Powell in her apartment in the '40s on the same spirret piano still in her living room.

For Taylor, it was a first performing duo piano.