Premise: A madrigal is a secular vocal music composition of the Renaissance and early Baroque eras. Traditionally, polyphonic madrigals are unaccompanied; the number of voices varies from two to eight, and most frequently from three to six. It is quite distinct from the Italian Trecento madrigal of the late 13th and 14th centuries, with which it shares only the name.
Hypothesis: The last  Italian Trecento madrigal occurred in the 15th century