26. (a) The second return map (light line), together with the first return map (dark line) for s = 2.
(b) The 2-cycle is shown by the dashed square.
(c) From the dashed square, we see one point, x, of the 2-cycle is less than 1/2, while the other, y, is greater than 1/2. Then using equation (2)
xn+1 = s*xn if xn <= 0.5
xn+1 = s*(1 - xn) if xn > 0.5
we see y = s*x and x = s*(1 - y). Combining these, x = s*(1 - s*x). Solving for x gives x = s/(1 + s2). Then y = s*x = s2/(1 + s2).

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