Assertion: progressive rock | /r/HasProperty | idea
Facets:
Source sentences:
text: By the early 1980s, progressive rock was thought to be all but dead as a style, an idea reinforced by the fact that some of the principal progressive groups had developed a more commercial sound. ...
text: According to musicologist John Covach, "by the early 1980s, progressive rock was thought to be all but dead as a style, an idea reinforced by the fact that some of the principal progressive groups has developed a more commercial sound.