Okay kiddo, so let's pretend we're building a really cool LEGO creation. And this creation is made up of smaller LEGO pieces that fit inside each other, like a bunch of Russian dolls.
Now, imagine we want to make sure our LEGO creation follows a certain set of rules, like it has to have a certain shape or color pattern. To do this, we can use something called a "nested stack automaton."
Basically, the "stack" part of the name means we have a pile of LEGO pieces that we can put on top of each other, like a stack of pancakes. And the "nested" part means there are more stacks inside each other, like the Russian dolls we talked about earlier.
Now, the "automaton" part is where things get a little trickier, but don't worry, we'll break it down. An automaton is like a little machine that follows a set of instructions to do something. In this case, our nested stack automaton is going to follow a set of instructions to make sure our LEGO creation is built correctly.
So, the automaton starts off with an empty stack. Then, as it looks at each LEGO piece, it decides whether or not to add it to the stack. If it decides to add it, it puts it on top of the stack. And if it decides not to add it, it takes the top piece off the stack.
Here's where the "nested" part comes in. Our LEGO creation might have smaller sections that are built separately and then put together. So, for each of these smaller sections, we can have a separate stack inside the main stack. It's like having a smaller Russian doll inside a bigger one.
The automaton can move between these different stacks to make sure everything fits together correctly, kind of like how we might switch between building the head and body of a LEGO person.
So, that's the basic idea of a nested stack automaton. It's like having a machine that can look at each LEGO piece, decide whether or not to add it, and make sure everything fits together in the end. Cool, huh?