The Alexander String Quartet, St. Lawrence University's quartet-in-residence, will perform in concert on Friday, Sept. 24, at 8 p.m. in Peterson-Kermani Performance Hall, Griffiths Arts Center, Canton. The event is open to the public, free of charge. They will perform the Shostakovich-Grafilo Prelude & Fugue in C Major, Op. 87, Nos. 1 and 20; Beethoven's "Elegischer Gesang," Op. 118, with the Laurentian Singers; Beethoven's Quartet in F Minor, Op. 95, "Serioso"; and Schubert's Quartet in D Minor, D. 810, "Death and the Maiden." They will also give an informal matinee performance, Thursday, Sept. 23, at noon in Peterson-Kermani Performance Hall.