CREATE TABLE table_11900773_4 (denomination VARCHAR, theme VARCHAR)

What denominations are the stamps with themes opera, l opold simoneau and pierrette alarie?
SELECT denomination FROM table_11900773_4 WHERE theme = "Opera, Léopold Simoneau and Pierrette Alarie"
SELECT "denomination" FROM "table_11900773_4" WHERE "Opera, Léopold Simoneau and Pierrette Alarie" = "theme"