Construct a support vector machine that computes the kernel function. Use four values of +1 and -1 for both inputs and outputs: [1, 1] (negative) [1, +1] (positive) [+1, 1] (positive) [+1, +1] (negative). Map the input [x1, x2] into a space consisting of x1 and x1x2. Draw the four input points in this space, and the maximal margin separator. What is the margin?