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mkultra

mkultra is a prompt tuning toolkit for GPT-2 and GPT-Neo.

Prompt tuning injects a string of 20-100 special tokens into the context in order to influence text generation. These tokens are trained on a corpus much like a finetune, but take up a fraction of the space. The Neuromancer example is only 401kb for 100 tokens.

Read the original paper: https://arxiv.org/abs/2104.08691

Text Generation

model = GPT2SoftPromptLM.from_pretrained("gpt2")
tokenizer = GPT2SPTokenizerFast.from_pretrained("gpt2")
generator = pipeline('text-generation', model=model, tokenizer=tokenizer)

sp = SoftPrompt.from_file("sample_sps/finetune/neuromancer_gpt2.json")
prompt = sp + "The sky over the port"
output = generator(prompt)

SoftPrompts can be concatenated at any point into your context as if they were strings. When the context is printed, SoftPrompts show up as human-readable tags for debugging. They also tokenize to the underlying number of tokens for easy budgeting.

See the text generation notebook for pointers on adding mkultra to your generator.

Training

For finetune-like soft prompts, the finetune notebook demonstrates training on a corpus.

For AI text adventures or writing, the World Info notebook notebook demonstrates tuning a soft prompt to describe a character or setting. This is highly experimental.

Limitations (for now)

• The Huggingface Trainer class should work as long as you set params=[model.get_soft_params()] on the optimizer, but it will still save full model checkpoints.
• mkultra syncs a set of special tokens between its tokenizers the scenes. Adding your own tokens may result in unexpected behaviour.