Question: In what year was the heavy metal band from Tronheim, Norway, who specializes in music that embodies a continuous move between explicit and implicit references to genres and strategies derived from cultural domains, formed?
Sentence (from "Progressive music"): The word "progressive" comes from the basic concept of "progress", which refers to development and growth by accumulation, and is often deployed in numerous music genres such as progressive country, progressive folk, progressive jazz, and (most significantly) progressive rock.
Relevant evidence: No