Status of C-runtime and majestic branch — parsing incomplete?

[Martin Gercke]

Hi,

I am currently experimenting with GF-WordNet to set up an example which - parses a German sentence - removes ambiguity by selecting the "correct" abstract syntax/meaning - makes translation to other languages. e.g. "Die Frau singt" -> an abstract syntax tree such as PredVPS (DetCN (DetQuant DefArt NumSg) (UseN woman_1_N)) (MkVPS (TTAnt TPres ASimul) PPos (UseV sing_2_V)) — with woman_1_N and sing_2_V picked as the intended WordNet senses — which then linearizes to English "the woman sings", Spanish "la mujer canta", Italian "la donna canta".

For this I would love to use the C runtime: the Haskell runtime enumerates all trees, which even for simple sentences explode to >1.000 leaves. C runtime promises bounded n-best parsing which could help. Also, I wanted to see how I can boil down the tree given that I know the "correct" abstract meaning of the nouns/verbs/adjectives involved.

So I went looking and found the majestic branch by looking at an issue (#130, "PGF as a database"), which looked very promising. I built the whole stack on WSL/Debian:

- C runtime (`src/runtime/c`, libpgf),

- Python binding (`src/runtime/python`),

- gf compiler (gf-4.0.0),

and downloaded the robust German grammar as an NGF.

`bootNGF`, `readNGF` and `lookupMorpho` work great and are *instant*

(mmap) — really nice.

The problem: parsing crashes. I un-commented `Concr.parse` in the binding wrapping `pgf_parse` to try and see if I could get it to run. It segfaults *inside the runtime* — even on the tiny `Food`

example compiled by the majestic `gf` itself (so it's not a format mismatch). The crashes seem to be in the LR machinery (`PgfParser::shift` dereferencing an invalid `shift->seq`, and a

`÷0` in `Production::operator new` where `lin->res.size()==0`). `git log` on `parser.cxx` shows active work ("an experimental left-corner table maker", etc.), so it looks like the parser on `majestic` is still mid-rewrite / incomplete.

Could somebody give me some guidance?

1. What's the current status of the C runtime overall, and which branch is the "live" one? 2. Which (C-runtime) runs on cloud.grammaticalframework.org/robust?

3. How does `majestic` relate to the other C-runtime branches? We see several (`pgf2-complete`, `lpgf`/`lpgf-memo`/`lpgf-string`, `concrete-new`, `compact-pgf`, `c-runtime`, ...)

4. Is there a branch/commit where end-to-end *parsing* with the NGF format actually works or is it even planned to get the parser running on the `majestic` branch at some point?

5. Any guidance on getting the C runtime + NGF running for parsing (not just lookup/linearization) would be hugely helpful.

Thanks a lot for any pointers! Martin

[Krasimir Angelov]

Hi Martin,

The parser in the majestic branch still has bugs. I plan to get back to it at the end of the summer when I will have less distractions from the many other things happening during the normal semester. The runtime that runs cloud.grammaticalframework.org/robust is in the one from the majestic branch, but is an older version which doesn't include the parser. The branches `pgf2-complete`, `lpgf`/`lpgf-memo`/`lpgf-string`, `concrete-new`, `compact-pgf`, `c-runtime` are other experimental versions which as far as I know are not used.

If you compile GF from the main branch and then compile the C runtime in src/runtime/c + the bindings in src/runtime/haskell-bind or src/runtime/python, then you can use the older C runtime which includes a parser but doesn't allow dynamic changes in the grammar. This also means that you have to compile GF WordNet with the compiler from the main branch.

Best,

Krasimir

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