> it's considered a bad thing to have problems that are essentially unsolvable for most of the class. It's really sad, for two reasons. First, most problems i

> it's considered a bad thing to have problems that are essentially unsolvable for most of the class. It's really sad, for two reasons. First, most problems in most AoPS books are solvable (or at least should be) for most of the class, especially if you exclude problems marked with asterisks. They're not that different from old Soviet or Polish math textbooks, and pretty much everyone was supposed to be able to solve that. Second, having only problems that everyone in the class can solve means that nobody in the class advances much. You can't learn to run 5k by walking 5k.