=========================================================================== CSC 363H Tutorial Exercises # 4 Spring 2007 =========================================================================== 1- Exercises (4.7) on page 183. Let T = {(i, j, k) | i, j, k are natural numbers}. Show that T is countable 2- Show that the set of irrational numbers is not countable. 3- Show that the set of numbers that are roots of a polynomials with rational coefficients is countable. These are called algebraic numbers. 4- Show that the language Rej_TM = { | M rejects w } is undecidable.