ELI5: Explain Like I'm 5

Henstock–Kurzweil integral

Hi there kiddo! Do you know what math is? It’s like solving puzzles with numbers! Today, we’re going to talk about a special kind of puzzle called the Henstock-Kurzweil Integral.

Now, let’s imagine we have a line graph of a function, just like the ones you draw in school. But instead of just figuring out the area under the line, the Henstock-Kurzweil Integral adds up all the little changes in the y-axis as well.

Imagine that you’re walking along the line graph, and every time you step on a point on the graph, you add up the difference in the y-axis between two points. Each step along the way, you add up all the differences and eventually, you’ll have the whole area under the graph!

The Henstock-Kurzweil Integral is special because it works even when the line is not a straight line or a perfect curve. It works for any function that has some kind of continuity and doesn't have any "gaps."

So, when you hear the words Henstock-Kurzweil Integral, you can think of it like walking along the line and adding up all the little changes in the y-axis as you go. Pretty cool, huh?