...or do they simply follow market movements? I mean from a purely mathematical perspective, many of the different types of odds (1X2, O/U, DNB and others) seem vulnerable to almost all types of arbitrage that I can think of that there aren't online calculators for. Sometimes I see this in opening lines. Sure, some of these types of bets have much lower limits than others, but still. Has anyone else noticed this? Does anyone have any idea how these market failures come to be?
To clarify, I'm not talking about arbitrage between books, but between different types of bets on the same event all placed at the same bookmaker.
(It's also possible that I simply don't understand the rules of the different bet types well enough)