Write formal for the following informal specifications. In each case the signature is {x N, x N}. Use angle bracket notation.

(a) x is bigger than x.

(b) x twice as big as x if x is smaller than 100; otherwise it doesnt matter what x is.

(c) x twice as big as x if x is smaller than 100; otherwise x is 200.

(d) x is at least 1 and x is smaller than x.