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"): Rooted in the idea of a cultural alternative, musical progressiveness embodies a continuous move between explicit and implicit references to genres and strategies derived from various cultural domains, such as European art music, Celtic folk, West Indian, or African.
Relevant evidence: Yes