zlacker

>>goranm+(OP)
> very few open-source LLMs explicitly claim they intentionally support structured data, but they’re smart enough and they have logically seen enough examples of JSON Schema that with enough system prompt tweaking they should behave.

Open source models are actually _better_ at structured outputs because you can adapt them using tools like JSONFormer et al that interact with the internals of the model (https://www.reddit.com/r/LocalLLaMA/comments/17a4zlf/reliabl...). The structured outputs can be arbitrary grammars, for example, not just JSON (https://github.com/outlines-dev/outlines#using-context-free-...).

>>twelft+08
> Open source models are actually _better_ at structured outputs because you can adapt them using tools like JSONFormer et al...

Yes, but you should also instruct the model to follow that specific pattern in its answer, or else the accuracy of the response degrades even though it's following your grammar/pattern/whatever.

For example, if you use Llama-2-7b for classification (three categories, "Positive", "Negative", "Neutral"), you might write a grammar like this:

```

root ::= "{" ws "sentiment:" ws sentiment "}"

sentiment ::= ("Positive" | "Neutral" | "Negative" )

ws ::= [ \t\n]*

```

But if the model doesn't know it has to generate this schema, the accuracy of classifications drops because it's trying to say other things (e.g., "As an AI language model...") which then get suppressed and "converted" to the grammar.

>>behnam+v9
Similarly, I think it is important to provide an “|” grammar that defines an error response, and explain to the model that it should use that format to explain why it cannot complete the requested operation if it runs into something invalid.

Otherwise, it is forced to always provide a gibberish success response that you likely won’t catch.

I’ve tested this with Mixtral, and it seems capable of deciding between the normal response and error response based on the validity of the data passed in with the request. I’m sure it can still generate gibberish in the required success response format, but I never actually saw it do that in my limited testing, and it is much less likely when the model has an escape hatch.

>>coder5+pP
Can you elaborate? So you instruct the model to either follow the grammar OR say why it can't do that? But the model has no idea this grammar exists (you can tell it the schema but the model doesn't know its tokens are going through a logprobs modification).

>>behnam+RV
No, the grammar can do OR statements. You provide two grammars, essentially. You always want to tell the model about the expected response formats, so that it can provide the best response it can, even though you’re forcing it to fit the grammar anyways.

In JSON Schema, you can do a “oneOf” between two types. You can easily convert a JSON Schema into the grammar that llama.cpp expects. One of the types would be the success response, the other type would be an error response, such as a JSON object containing only the field “ErrorResponse”, which is required to be a string, which you explain to the model that this is used to provide an explanation for why it cannot complete the request. It will literally fill in an explanation when it runs into troublesome data, at least in my experience.

Then the model can “choose” which type to respond with, and the grammar will allow either.

If everything makes sense, the model should provide the successful response you’re requesting, otherwise it can let you know something weird is going on by responding with an error.