Hi there! So, do you know what a theorem is? It's like a really special and important that someone proves using math. Sumihiro's Theorem is one of those special theorems.
Now, imagine you have a really pretty shape (we call it a "complex projective algebraic variety", but we'll just call it a "shape" for now) that's a lot like a puzzle. But, you know how puzzles come in different shapes and sizes? Well, this shape might have some parts that don't quite fit with the others.
Sumihiro's Theorem helps us understand how to measure and describe this shape by breaking it into lots of smaller (and simpler) shapes that fit together perfectly. This makes it easier for us to understand the whole shape.
It's like when you have a really big ice block and you want to make a snowman. You don't just try to make one big snowball - you make lots of smaller snowballs and stack them on top of each other to make the snowman. That's what Sumihiro's Theorem helps us do with this shape.
So, in short, Sumihiro's Theorem helps us break down a complicated shape into smaller, simpler pieces that we can understand better. It's like a puzzle solver for mathematicians!