jfkback/hypencoder.8_layer

Model Card

This is the official model from the paper Hypencoder: Hypernetworks for Information Retrieval.

Model Details

This is a Hypencoder Dual Encoder. It contains two trunks the text encoder and Hypencoder. The text encoder converts items into 768 dimension vectors while the Hypencoder converts text into a small neural network which takes the 768 dimension vector from the text encoder as input. This small network is then used to output a relevance score. To use this model please take a look at the Github page which contains the required code and details on how to run the model.

Model Variants

We released the four models used in the paper. Each model is identical except the small neural networks, which we refer to as q-nets, have different numbers of hidden layers.

Huggingface Repo	Number of Layers
jfkback/hypencoder.2_layer	2
jfkback/hypencoder.4_layer	4
jfkback/hypencoder.6_layer	6
jfkback/hypencoder.8_layer	8

Usage

from hypencoder_cb.modeling.hypencoder import Hypencoder, HypencoderDualEncoder, TextEncoder
from transformers import AutoTokenizer

dual_encoder = HypencoderDualEncoder.from_pretrained("jfkback/hypencoder.6_layer")
tokenizer = AutoTokenizer.from_pretrained("jfkback/hypencoder.6_layer")

query_encoder: Hypencoder = dual_encoder.query_encoder
passage_encoder: TextEncoder = dual_encoder.passage_encoder

queries = [
    "how many states are there in india",
    "when do concussion symptoms appear",
]

passages = [
    "India has 28 states and 8 union territories.",
    "Concussion symptoms can appear immediately or up to 72 hours after the injury.",
]

query_inputs = tokenizer(queries, return_tensors="pt", padding=True, truncation=True)
passage_inputs = tokenizer(passages, return_tensors="pt", padding=True, truncation=True)

q_nets = query_encoder(input_ids=query_inputs["input_ids"], attention_mask=query_inputs["attention_mask"]).representation
passage_embeddings = passage_encoder(input_ids=passage_inputs["input_ids"], attention_mask=passage_inputs["attention_mask"]).representation

# The passage_embeddings has shape (2, 768), but the q_nets expect the shape
# (num_queries, num_items_per_query, input_hidden_size) so we need to reshape
# the passage_embeddings.

# In the simple case where each q_net only takes one passage, we can just
# reshape the passage_embeddings to (num_queries, 1, input_hidden_size).
passage_embeddings_single = passage_embeddings.unsqueeze(1)
scores = q_nets(passage_embeddings_single)  # Shape (2, 1, 1)
# [
#    [[-12.1192]],
#    [[-13.5832]]
# ]

# In the case where each q_net takes both passages we can reshape the
# passage_embeddings to (num_queries, 2, input_hidden_size).
passage_embeddings_double = passage_embeddings.repeat(2, 1).reshape(2, 2, -1)
scores = q_nets(passage_embeddings_double)  # Shape (2, 2, 1)
# [
#    [[-12.1192], [-32.7046]],
#    [[-34.0934], [-13.5832]]
# ]

Citation

BibTeX:

@misc{killingback2025hypencoderhypernetworksinformationretrieval,
      title={Hypencoder: Hypernetworks for Information Retrieval}, 
      author={Julian Killingback and Hansi Zeng and Hamed Zamani},
      year={2025},
      eprint={2502.05364},
      archivePrefix={arXiv},
      primaryClass={cs.IR},
      url={https://arxiv.org/abs/2502.05364}, 
}