Which opera  Pelléas et Mélisande and Die schweigsame Frau has fewer acts ?
Pelléas et Mélisande (opera) Pelléas et Mélisande ("Pelléas and Mélisande") is an opera in five acts with music by Claude Debussy. The French libretto was adapted from Maurice Maeterlinck's Symbolist play "Pelléas et Mélisande". It premiered at the Opéra-Comique in Paris on 30 April 1902 with Jean Périer as Pelléas and Mary Garden as Mélisande in a performance conducted by André Messager, who was instrumental in getting the Opéra-Comique to stage the work. The only opera Debussy ever completed, it is considered a landmark in 20th-century music.
Die Hochzeit Die Hochzeit ("The Wedding", WWV 31) is an unfinished opera by Richard Wagner which predates his completed works in the genre. Wagner completed the libretto, then started composing the music in the second half of 1832 when he was just nineteen. He abandoned the project after his sister Rosalie, who was the main supporter and the spokesman of the family, expressed her disgust at the story. Wagner destroyed the libretto.