让Transformer通过迭代修正实现更准确的自回归生成。
Closed-Loop Transformers: Autoregressive Modeling as Iterative Latent Equilibrium
- 引入闭环预测机制,让模型在生成每个词前反复优化隐状态直至自洽。
- 在二进制奇偶任务中,复杂序列上性能提升达8.07%,平均提升3.28%。
- 适合需要长程推理与高一致性任务,如复杂规划和事实生成。
当前自回归Transformer采用开环模式:每个隐藏状态仅通过一次前向传播计算且不再修正,导致错误在序列中持续累积。我们指出这一开环瓶颈是长距离推理、事实一致性和多步规划失败的根本原因。为此,提出闭环预测原则:模型需迭代精炼隐表示,直至达到自洽平衡后再确定每个词。我们将其实例化为等价变压器(EqT),在标准Transformer层中加入等价精炼模块,通过潜空间梯度下降最小化一个学习到的能量函数。该能量函数无须外部监督即可强制双向预测一致性、情景记忆连贯性及输出置信度。理论上,我们证明EqT在潜能量模型中执行近似最大后验推断,建立线性收敛保证,并表明精炼能有效提升单次推断表现不佳的困难样本。该框架统一了深度等价模型、扩散语言模型与测试时训练。初步实验在二进制奇偶任务中显示,复杂序列平均性能提升3.28%,最差情形下提升达8.07%,验证了反思能力随任务难度增加而提升。
原文摘要 · Abstract (English)
Contemporary autoregressive transformers operate in open loop: each hidden state is computed in a single forward pass and never revised, causing errors to propagate uncorrected through the sequence. We identify this open-loop bottleneck as a fundamental architectural limitation underlying well-documented failures in long-range reasoning, factual consistency, and multi-step planning. To address this limitation, we introduce the closed-loop prediction principle, which requires that models iteratively refine latent representations until reaching a self-consistent equilibrium before committing to each token. We instantiate this principle as Equilibrium Transformers (EqT), which augment standard transformer layers with an Equilibrium Refinement Module that minimizes a learned energy function via gradient descent in latent space. The energy function enforces bidirectional prediction consistency, episodic memory coherence, and output confidence, all computed without external supervision. Theoretically, we prove that EqT performs approximate MAP inference in a latent energy-based model, establish linear convergence guarantees, and show that refinement improves predictions precisely on hard instances where one-shot inference is suboptimal. The framework unifies deep equilibrium models, diffusion language models, and test-time training as special cases. Preliminary experiments on the binary parity task demonstrate +3.28% average improvement on challenging sequences, with gains reaching +8.07% where standard transformers approach random performance, validating that the benefit of deliberation scales with task difficulty. Just as attention mechanisms resolved the sequential bottleneck of recurrent networks, we propose that closed-loop equilibrium may resolve the commitment bottleneck of open-loop autoregression, representing a foundational step toward language models.
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