ELI5: Explain Like I'm 5

Hilbert's fourth problem

Imagine you have a puzzle that is made up of tiny blocks or pieces. The puzzle is called a geometric puzzle because it involves shapes like squares, triangles, and circles. Now, what if someone tells you to take these pieces and put them together in a way that fills up a space without leaving any gaps or overlaps? This is called a tiling problem.

Hilbert's fourth problem is all about solving these tiling problems. It's named after a mathematician named David Hilbert who thought it would be interesting to find out if there are any rules or algorithms that we can use to solve any kind of tiling problem.

To help solve this problem, Hilbert and other mathematicians tried to come up with formulas, or math equations, that could predict whether a given tiling problem can be solved or not. They also looked at the history of tiling problems, studying patterns that have worked and those that have not.

Hilbert's solution to the fourth problem was to show that there could be a way to find a general equation, or a rule for solving tiling problems. This would mean that anyone could use it to solve tiling problems and create beautiful geometric patterns.

In summary, Hilbert's fourth problem is about figuring out how to solve any tiling problem by finding a general equation or rule that would work for any shape or size of the puzzle pieces.