Consider the correctness of the class MyS tack in Section 18.3.

(a) The method size was verified in consmt with initialization of an object using the class constructor. Write an appropriate Hoare triple and then verify the methods i ze for all other states that the object may have.

(b) Write an appropriate Hoare triple and then verify the method push.

Prove by inductiOn that the Haskell operator++ is associative, using its recursive definition named cat that is given in this chapter. That is, show that for all lists xs, ys, and zs:

Thatis,thisisequivalentto (xs ++ ys) ++ zs = xs ++ (ys ++ zs).

Transcribed Image Text:

cat (cat xs ys) zs - cat xs (cat ys zs) cat (cat xs ys) zs - cat xs (cat ys zs)