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1. Introduction

This repository contains the official implementation for the paper: Conditional Memory via Scalable Lookup: A New Axis of Sparsity for Large Language Models.

Abstract: While Mixture-of-Experts (MoE) scales capacity via conditional computation, Transformers lack a native primitive for knowledge lookup. To address this, we explore conditional memory as a complementary sparsity axis, instantiated via Engram, a module that modernizes classic $N$-gram embeddings for $\mathcal{O}(1)$ lookup.

Key Contributions:

• Sparsity Allocation: We formulate the trade-off between neural computation (MoE) and static memory (Engram), identifying a U-shaped scaling law that guides optimal capacity allocation.
• Empirical Verification: Under strict iso-parameter and iso-FLOPs constraints, the Engram-27B model demonstrates consistent improvements over MoE baselines across knowledge, reasoning, code and math domains.
• Mechanistic Analysis: Our analysis suggests that Engram relieves early layers from static pattern reconstruction, potentially preserving effective depth for complex reasoning.
• System Efficiency: The module employs deterministic addressing, enabling the offloading of massive embedding tables to host memory with minimal inference overhead.

2. Architecture

The Engram module augments the backbone by retrieving static $N$-gram memory and fusing it with dynamic hidden states. The architecture is shown below (drawio provided):

3. Evaluation

Scaling Law

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Large Scale Pre-training

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Long-context Training

4. Case Study of Engram

5. Quick Start

We recommend using Python 3.8+ and PyTorch.

pip install torch numpy transformers sympy

We provide a standalone implementation to demonstrate the core logic of the Engram module:

python engram_demo_v1.py

⚠️ Note: The provided code is a demonstration version intended to illustrate the data flow. It mocks standard components (like Attention/MoE/mHC) to focus on the Engram module.

6. License

The use of Engram models is subject to the Model License.

7. Contact

If you have any questions, please raise an issue or contact us at service@deepseek.com.