Closed world assumption

Okay kiddo, let's talk about the closed world assumption. Imagine that you are playing a game and your mom tells you to get all the toys in your room. You look around and see a puzzle on the floor, a book on the shelf, and a teddy bear on your bed. You collect these toys and gave it to your mom, but she says you forgot a toy car.

This is where the closed world assumption comes in. It means that you only know about the things that you can see or touch in your room, and you assume that everything else is not there. So, in this case, you assumed that there were no other toys in your room besides what you saw, but your mom can tell you about the toy car that was hiding under your bed because she has more knowledge about your room than you do.

The closed world assumption is used in computer science too, especially with databases. Just like your mom, computer programs have a lot more information than what they show you, but they also make assumptions about what they don't know. For example, if you ask a computer program to search for a specific item in a database, it will assume that if it can't find it, then it doesn't exist in the database.

So, the closed world assumption is like a way for computer programs to work with the information they have, instead of trying to guess what they don't know. Just like you only picked up the toys you saw in your room, computer programs only work with the data they have, and assume that everything else is not there.