I have been working on a better implementation of the LR algorithm to improve parse.y using Lrama. In Lrama 0.7, which is designed for CRuby 3.5, the parser can now be generated using IELR, an algorithm that is one step further from LALR, with a wider range of languages that can be parsed than LALR. In this presentation, I will discuss the detailed theory of IELR and its implementation in Lrama.