General Directional Bottom-Up Parsing

As explained in Section 3.2.2, directional bottom-up parsing is conceptually very simple. At all times we are in the possession of a sentential form that derives from the input text through a series of leftmost reductions. These leftmost reductions during parsing correspond to rightmost productions that produced the input text: the first leftmost reduction corresponds to the last rightmost production, the second corresponds to the one but last, etc.