Program refinement

Program refinement is like building with Lego blocks. You start with a basic idea of what you want to make, like a house. You start with a few blocks, but you need more blocks to create the whole house.

Similarly, in program refinement, you start with a basic idea of what you want to make, like a program. You write a few lines of code, but you need to add more lines of code to create the whole program.

Just like with Lego blocks, you need to follow some rules when adding more pieces. You can't just add any block you want; it has to fit with the blocks you have already placed.

In program refinement, you also need to follow rules when adding more code. You can't just add any code you want; it has to work with the code you have already written.

And just like with Lego blocks, you can make changes to your program as you go along. If you make a mistake, you can take out the bad code and replace it with good code, just like taking out a block and replacing it with a better one.

In summary, program refinement is the process of building a program bit by bit, adding more code to make it complete, and making changes as needed. It's like building with Lego blocks, following rules, and making improvements along the way.