# How to simplify the actual function using K-maps?

So I'm trying to learn how to use Karnaugh maps. I've found what are the rules of simplification and how to apply them but every tutorial or lesson I find uses some generic function like "Here's how to do Karnaugh maps for three variables" and someone just does the truth table for A, B, C and then creates a map. But what if I wanted to simplify some specific function, say F=AB+A(B+C)? I can't just make a truth table for A, B, C and their sum because it's just not enough. So how should I solve it using Karnaugh maps? Should I make a "typical" truth table, i.e. for A, B, C, AB, B+C, A(B+C)? But how should this help me in drawing the map and simplyfing?

Could someone please tell me a little about it or point some direction? I'd really like to learn this but just can't get a grasp of it.

• "say F=AB+A(B+C)? I can't just make a truth table for A, B, C and their sum because it's just not enough." Why can't you make a truth table from the formula? Write down all possibilities for A, B and C followed by the resulting value for F. Make a table one column for each variable A,B,C,F and start filling it for ABC with all possibilities (there are eight), then for each line calculate F. Mar 24, 2013 at 13:01
• Oh, I believe I expressed myself wrong. As I write later: "Should I make a "typical" truth table, i.e. for A, B, C, AB, B+C, A(B+C)? But how should this help me in drawing the map and simplyfing?". I know I can do the truth table - what I don't know is how such a table should help me in drawing the final map. Mar 24, 2013 at 13:16
• The truth table for F would only need columns for A, B, C and F. You can add columns for AB, B+C and A(B+C) to aid in the intermediate determination of what the values of F will be for each ABC combination. But that may not be necessary if you can work out AB+A(B+C) in your head for each of the cases. I've shown an answer that shows the truth table to K-Map translation template for you to work with. Mar 24, 2013 at 14:39