To find the PMF of Y given X, where Y is defined as Y = sin(π/(2X)) and p_X[k] = 1/5 for k = 0, 1, 2, 3, 4, one must consider the transformation of the random variable X. The discussion highlights the challenge of defining Y when X equals zero, as it leads to an undefined expression. Participants express confusion regarding the notation p_X[k] and its implication for the probability distribution of X. The thread indicates that the problem has been previously addressed, yet no clear solution is provided within the discussion. Overall, the focus remains on understanding the transformation and its implications for calculating the PMF of Y.