---
title: Mixture-of-Recursions (MoR)
type: vocabulary
url: "https://www.envisioning.com/vocab/mixture-of-recursions"
summary: Transformer architecture that routes tokens through varying numbers of weight-tied recurrent iterations via learned token-level recursion depths.
year: 2025
generality: 0.50
---

# Mixture-of-Recursions (MoR)

Transformer architecture that routes tokens through varying numbers of weight-tied recurrent iterations via learned token-level recursion depths.
Mixture-of-Recursions (MoR) is a transformer architecture introduced by Bae et al. in July 2025. It combines weight-tied recurrent depth with a learned router: each transformer block is applied multiple times to the same token representation, with the number of applications chosen per token by the router. Easy tokens loop once; harder tokens loop two or three times.

MoR extends routing schemes from mixture-of-experts by routing on recursion depth rather than expert identity. The original paper explores both token-choice routing (each token picks its own depth) and expert-choice routing (each depth level picks its tokens). On language modeling benchmarks, MoR matches larger non-recursive baselines with a fraction of the parameters and FLOPs.

Because weights are shared across recursion steps, MoR admits a key-value cache reuse trick that keeps memory cost flat regardless of per-token loop count. The architecture has been used as a reference for inference-efficient long-context and reasoning models in 2025 and 2026.

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Source: Envisioning — Technology Research Institute (https://www.envisioning.com/vocab/mixture-of-recursions)