CLASSICAL: Virginia Pleasants, fortepiano; music of Bach and Beethoven; B.U. Concert Hall; Monday at 8 p.m.

LECTURE: Composers' Forum Series; Alberto Ginastera; B.U. Concert Hall; Tuesday at 12:30 p.m.

LECTURE: "Our View of 15th and 16th Century Music: Do We Proceed from Correct Premises?"; Martin Staehelin; Marshall Room, B.U. School of Music; Tuesday at 8 p.m.

THEATER. "Playboy of the Western World"; B.U. Theater; Thursday-Saturday at 8 p.m.

WORKSHOP: Opera Workshop; Adelaide Bishop, director; Warren George Wilson, music director; "The Four Note Opera"; B.U. Concert Hall; Thursday and Friday at 8 p.m.

CLASSICAL: Carol Lieberman, baroque violin, and Mark Kroll, harpsichord and fortepiano; music of LeDuc, Moxart, Bach and Balbastre; Grand Ballroom East, Park Plaza Hotel; Thursday at 8:30 p.m.

EXHIBIT: "Invisible Light: Infrared Photography--A Smithsonian Institution Traveling Exhibit"; B.U. Gallery; opens Saturday

CLASSICAL: B.U. Concert Choir, Women's Chorus and Repertory Orchestra; Tom Hall and Thomas Dunn, directors; music of Hindemith, Strvinsky and Faure; Marsh Chapel, 735 Commonwealth Ave., Boston; Sunday at 3 p.m.

FILM: "Das Testament des Dr. Mabuse"; GSU, Rm. 314; Wednesday at 7 p.m.