"Snelling, Michel. General Context-Free Parsing in Time $n^2$,
in International Computing Symposium 1973, pages 19-24, Amsterdam, 1974. North-Holland.
It is extremely unlikely that the claim in the title holds, but no refutation has been published to date; in fact, the paper does not seem to be referenced anywhere. The algorithm is described in reasonable detail, but not completely. Filling in the last details allows some examples in the paper to be reproduced, but not all at the same time, it seems. Attempts at implementations can be found in this zip file. Further clarification would be most welcome."
"Snelling, Michel. General Context-Free Parsing in Time $n^2$, in International Computing Symposium 1973, pages 19-24, Amsterdam, 1974. North-Holland. It is extremely unlikely that the claim in the title holds, but no refutation has been published to date; in fact, the paper does not seem to be referenced anywhere. The algorithm is described in reasonable detail, but not completely. Filling in the last details allows some examples in the paper to be reproduced, but not all at the same time, it seems. Attempts at implementations can be found in this zip file. Further clarification would be most welcome."