Original title: Beyond Magnitude: Contrastive Routing for Modular Mixture-of-Experts
Nikolaos Xiros, Dimitrios Damianos, Maria-Eleni Zoumpoulidi, Leon Voukoutis +2 · September 2026
Some AI models use a Mixture-of-Experts setup, where smaller sub-networks, called experts, handle different pieces of data. Usually, a router decides which expert gets each token, meaning each piece of text. But these decisions rely on raw representations that share too much background information across all tokens, which keeps experts from truly specializing. To fix this, researchers built the Contrastive Routing Mechanism, or CoRM. Instead of looking at raw token size alone, CoRM compares each token against a running average of the layer's states. It scores each expert on the gap between the token and that shared baseline. This focuses the routing decisions, aligns expert boundaries with linguistic structure, and boosts reasoning accuracy across nine benchmarks while adding very little computational cost.
When packing for a trip, you might sort clothes by color, but this doesn't consider how often you'll wear them. This leads to inefficient packing where you forget important items. In this paper, the system sorts AI experts by comparing each input to a moving average of past inputs, matching them based on specific needs rather than a basic property.
This improves language models used in AI assistants, making them more accurate at reasoning tasks without significant extra computing cost. It benefits anyone relying on AI for problem-solving by providing more reliable outputs.
The abstract only reports results on nine zero-shot reasoning benchmarks; it doesn't show performance for other tasks like translation or coding. Also, the minimal cost increase might not be consistent across all model sizes or hardware.
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Beyond Magnitude: Contrastive Routing for Modular Mixture-of-Experts — Nikolaos Xiros, Dimitrios Damianos, Maria-Eleni Zoumpoulidi et al.
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.