In this example, all variables are boolean

The training set consists of the following examples:

        x1 x2 x3 f
        1  0  0  0
        0  1  1  0
        1  0  1  1

The learning model consists of {AND, OR, XOR, NAND, NOR, x1 /\ x3}

There error for each model is 1/3, 2/3, 2/3,2/3, 1/3, 0/3. So x1 /\ x3 is the best.

The actual target function was XOR(x2,x3).

The real error in this choice was 4/8.

The real error for the example 1 choice was 5/8.

The real error for OR is only 3/8.