Abba, the Beatles, U2 and the Back Street Boys change their music style.
They now adopt break dance, rap, techno and blues genres.
Their concert is on Saturday, Sunday, Monday and Tuesday at 21h, 21h30, 22h and 23h30.

Hints    :  - U2 started at 21h but not on a Tuesday or Sunday.
                 - The techno concert started after 21h but not on Tuesday or Sunday.
                 - Saturday's concert did not start at 22h.
                 - The rap group, Abba, did not play on Sunday nor at 22h on any other night.
                 - The blues ensemble is not U2 or the Beatles but started before 22h.

Questions : What kind of music and at what time does each group play?

See answer