Chopin melodies used as a basis for jazz improvisation? In the wrong hands, the results could be truly catastrophic. Yet it's a notion with great appeal for celebrated Dutch piano marvel Peter Beets. ''Why, melodic embellishment is at the heart of everything that Chopin wrote!'' enthuses Peter. ''In fact, he was composing tunes ideal for bebop, although he couldn't have known it at the time.'' It's a happy coincidence that the fifth Criss Cross CD under Beets' leadership arrives during the bicentennial year of Chopin's birth. But it's clearly not a project haphazardly thrown together at the last moment. Instead, Peter recruited three of New York's premier jazzmen - guitarist Joe Cohn, bassist Reuben Rogers and drummer Greg Hutchinson - as co-conspirators.