Which opera  Pelléas et Mélisande and Die schweigsame Frau has fewer acts ?
Die schweigsame Frau Die schweigsame Frau ("The Silent Woman"), Op. 80, is a 1935 opera in three acts by Richard Strauss with libretto by Stefan Zweig after Ben Jonson's "Epicoene, or the Silent Woman".
Lohengrin (Sciarrino) Lohengrin "(Azione invisibile per solista, strumenti e voci)" is an operatic monodrama by the Italian composer Salvatore Sciarrino. Premiered in 1982 in Milan the work was later revised by Sciarrino and the new version was premiered in on 9 September 1984 in Catanzaro. The opera, which is less than an hour long, is loosely based on the plot of Wagner’s opera of the same name.