SimMerge: Learning to Select Merge Operators from Similarity Signals

Fuente: arXiv
Saved in:
Bibliographic Details
Main Authors: Bolton, Oliver, Aakanksha, Ahmadian, Arash, Hooker, Sara, Fadaee, Marzieh, Ermis, Beyza
Format: Preprint
Published: 2026
Subjects:
Online Access:
Tags: Add Tag
No Tags, Be the first to tag this record!
_version_ 1866908804385341440
author Bolton, Oliver
Aakanksha
Ahmadian, Arash
Hooker, Sara
Fadaee, Marzieh
Ermis, Beyza
author_facet Bolton, Oliver
Aakanksha
Ahmadian, Arash
Hooker, Sara
Fadaee, Marzieh
Ermis, Beyza
contents Model merging combines multiple models into a single model with aggregated capabilities, making it a powerful tool for large language model (LLM) development. However, scaling model merging is challenging: performance depends on the choice of merge operator, model subset, and merge order, often requiring expensive merge-and-evaluate searches. In this work, we introduce SimMerge, a predictive merge-selection method that identifies high-performing merges using inexpensive, task-agnostic similarity signals between models. Given a small set of unlabeled probes, SimMerge extracts functional and structural features to predict the performance of candidate two-way merges, enabling merge operator, order and model subset selection without iterative evaluation. We show that SimMerge consistently outperforms the best fixed merge operator across 7B-parameter LLMs and generalizes to multi-way merges and 111B-parameter LLMs without retraining. We further introduce a bandit variant that supports adding new tasks and operators online. Our results suggest that learning how to merge enables scalable model composition when checkpoint catalogs are large and evaluation budgets are limited.
format Preprint
id arxiv_https___arxiv_org_abs_2601_09473
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle SimMerge: Learning to Select Merge Operators from Similarity Signals
Bolton, Oliver
Aakanksha
Ahmadian, Arash
Hooker, Sara
Fadaee, Marzieh
Ermis, Beyza
Machine Learning
Artificial Intelligence
Model merging combines multiple models into a single model with aggregated capabilities, making it a powerful tool for large language model (LLM) development. However, scaling model merging is challenging: performance depends on the choice of merge operator, model subset, and merge order, often requiring expensive merge-and-evaluate searches. In this work, we introduce SimMerge, a predictive merge-selection method that identifies high-performing merges using inexpensive, task-agnostic similarity signals between models. Given a small set of unlabeled probes, SimMerge extracts functional and structural features to predict the performance of candidate two-way merges, enabling merge operator, order and model subset selection without iterative evaluation. We show that SimMerge consistently outperforms the best fixed merge operator across 7B-parameter LLMs and generalizes to multi-way merges and 111B-parameter LLMs without retraining. We further introduce a bandit variant that supports adding new tasks and operators online. Our results suggest that learning how to merge enables scalable model composition when checkpoint catalogs are large and evaluation budgets are limited.
title SimMerge: Learning to Select Merge Operators from Similarity Signals
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2601.09473