Critically discuss the following statements about stock market efficiency:
(a) The weak form of the efficient market hypothesis implies that it is possible for investors to generate abnormal returns by analysing changes in past share prices.
(b) The semi-strong form of the efficient market hypothesis implies that it is possible for an investor to earn superior returns by studying company accounts, newspapers and investment journals, or by purchasing reports from market analysts.
(c) The strong form of the efficient market hypothesis implies that, as share prices reflect all available information, there is no way that investors can gain abnormal returns.