In April, the Stone adopted a new policy, booking a single musician or group for a six-night run from Tuesday to Sunday. But when you give a week to someone like Fred Frith, who opened a Stone engagement in a duet with Laurie Anderson on Tuesday night, the results still allow for plenty of variety and intrigue. Mr. Frith, a British guitarist, composer and improviser, has a résumé comparable with Mr. Zorn’s in its multifarious disposition. He was a founder of the avant-garde rock group Henry Cow, which formed in 1968 and ran for a decade. In 1974, he issued “Guitar Solos,” the first in an influential series of records demonstrating his idiosyncratic approach to improvisation.