Lambda Calculus

2. For each of the following terms, identify the free variables in each term and identify which terms are closed: t1 = x t2 = ( lambda y y) t3 = (lambda x (x x)) t4((lambda x x) x) t5 = ( lambda x (lambda y (x y))) t6 = ( lambda x (x y)) t7((lambda yx) y) t8(( ((lambda x x) z) x) ((lambda y (z y)) y))