Valiant's general context free parser is one of the few very well known general context free parsers. Its claim to fame is that given any context-free grammar, it can parse any strings in that grammar in less than O(N^3) time, by leveraging advances matrix multiplication. Unfortunately, lucid explanations of what Valiant's algorithm does is somewhat hard to find. I have just written a live notebook post that explains the Valiant's parser, and lets you play with the algorithm directly.

https://rahul.gopinath.org/post/2023/03/16/valiant-parser/

#parsing #context-free

An unforeseen (or perhaps foreseeable) issue; Most foot guns I have learned to avoid in Python are present in GPT4 generated code, and it is not immediately obvious anymore. Chased a surprising bug and found 
             C = [[{}] * m for _ in range(m)]
followed by 
         C[i][j][k] = "V"
buried deep. Because I trusted GPT4 (it aught to be good at these things) I failed to recognize this pattern :/

It is very mesmerizing to get chatGPT+ (GPT4) to write code for you. It keeps making different mistakes every time, and inventing newer explanations!

Experimenting with the new Bing (Sydney?), it seems that it has problems with citations still. In the below, all the links to the arxiv.org are the same paper I wrote some time back, and the one in research.org is also the same paper, albeit in a different cite.

To those who are struggling with Microsoft's outlook, please give #mutt http://www.mutt.org/ a try. It works very well with outlook (beyond some configuration), has sane searching capabilities, and does exactly what you want it to do. I have been using it to survive email in #usyd.