Solutions have varying ranges of coverage. It is often assumed that when it is said, "a problem is solved". That is for one one hundred perecent of the probelm's instances. That might be. It might not. In many instances, such is said. When, a problem has a clear solution, in a meaningful number of the problem instances. That might only be in the normal case or roughly ninety-five percent of the time. Different fields has differing criteria for what be considered a "general solution".