Ill-posed problem

An ill-posed problem is a type of problem that is tricky and has no definite answer. It's like trying to put together a jigsaw puzzle with some of the pieces missing - you don't know which pieces you're missing and it can be very difficult to figure out how to put it all together. In mathematics, an ill-posed problem is a problem that doesn't have a unique solution or that it is very hard to find the right solution.