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Demetrio e Polibio (Italian pronunciation: [deˈmɛːtrjo e ppoˈliːbjo]; Demetrius and Polybius) is a two-act operatic dramma serio by Gioachino Rossini to a libretto by Vincenzina Viganò-Mombelli. The opera was orchestrated for flute, oboes, clarinets, basson, horns, trumpets, and strings. The opera was not professionally staged until 18 May 1812, when it premiered at Rome's Teatro Valle.