Complex sentence: The council met, deposed both antipopes, and elected Alexander V. Gerson officially addressed the new pope on his duties in "Sermo coram Alexandro Papa in die ascensionis in concilio Pisano" (ii.131).
Split into simpler sentences: The council met, deposed both antipopes, and elected Alexander V. Gerson was chosen to address the new pope on the duties of his office. He did so in his "Sermo coram Alexandro Papa in die ascensionis in concilio Pisano" (ii.131).