Answer: sure bets
At last!!! Someone answered !!!
Dude Lyhnus thank you for letting me know but for 3 days all I have to do is read ..
What struck me is that I didn't see anywhere in a double combination of a double opportunity, eg 1,20 with a split under / over odds, or goal / no goal, or 1 dnb / 2 dnb so that 1,20 * 1,90 = 2,28 ... which means positive rake and that it gets the value of the sure bet ...
Also another thought that came to me looking for returns is:
sure bet with no induction ... what do I mean ??????
I exclude in a match a possible example of just getting 1 goals, so I play under 0.5 and over 1.5 ... Again positive rake !!