Assertion: piano's keyboard | /r/CapableOf | introduce new thematic material
Facets:
value: in its first entry
type: TEMPORAL
Source sentences:
text: The keyboard parts of the concertos were almost invariably based on material presented in the ritornelli, and it was probably J.C. Bach, whom Mozart admired, who introduced the structural innovation of allowing the keyboard to introduce new thematic material in its first entry.