The following patterns are basic to all the binary functions we will use in this course, including the additional signals **X (=AN)** and **Y (=ON)**. They should be learned well. Keep in mind that while we use **P** and **Q** for convenience in these patterns, we are always thinking of the relationship between a lefthand module (call it the circle) and a righthand module (call it the box). These circle-box rules apply to all substitution instances of the **P **and **Q** in the model.

P Q || PQA | PQB | PQC | PQM | PQO | PQX | PQY

1..1........1.........1.........1.........0.........1.........0.........0

1..0........0.........0.........0.........1.........1.........1.........0

0..1........0.........0.........1.........1.........1.........1.........0

0..1........0.........1.........1.........0.........0.........1.........1

The number of lines in a truth table double with each new variable. With **R** added to the far right of the table, there will be four lines in which **P** is true and four in which it is false.

*Experiment with the program PLN2VAL that is provided on your disk.*