Tower+: Bridging Generality and Translation Specialization in Multilingual LLMs

Fuente: arXiv
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Main Authors: Rei, Ricardo, Guerreiro, Nuno M., Pombal, José, Alves, João, Teixeirinha, Pedro, Farajian, Amin, Martins, André F. T.
Format: Preprint
Published: 2025
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author Rei, Ricardo
Guerreiro, Nuno M.
Pombal, José
Alves, João
Teixeirinha, Pedro
Farajian, Amin
Martins, André F. T.
author_facet Rei, Ricardo
Guerreiro, Nuno M.
Pombal, José
Alves, João
Teixeirinha, Pedro
Farajian, Amin
Martins, André F. T.
contents Fine-tuning pretrained LLMs has been shown to be an effective strategy for reaching state-of-the-art performance on specific tasks like machine translation. However, this process of adaptation often implies sacrificing general-purpose capabilities, such as conversational reasoning and instruction-following, hampering the utility of the system in real-world applications that require a mixture of skills. In this paper, we introduce Tower+, a suite of models designed to deliver strong performance across both translation and multilingual general-purpose text capabilities. We achieve a Pareto frontier between translation specialization and multilingual general-purpose capabilities by introducing a novel training recipe that builds on Tower (Alves et al., 2024), comprising continued pretraining, supervised fine-tuning, preference optimization, and reinforcement learning with verifiable rewards. At each stage of training, we carefully generate and curate data to strengthen performance on translation as well as general-purpose tasks involving code generation, mathematics problem solving, and general instruction-following. We develop models at multiple scales: 2B, 9B, and 72B. Our smaller models often outperform larger general-purpose open-weight and proprietary LLMs (e.g., Llama 3.3 70B, GPT-4o). Our largest model delivers best-in-class translation performance for high-resource languages and top results in multilingual Arena Hard evaluations and in IF-MT, a benchmark we introduce for evaluating both translation and instruction-following. Our findings highlight that it is possible to rival frontier models in general capabilities, while optimizing for specific business domains, such as translation and localization.
format Preprint
id arxiv_https___arxiv_org_abs_2506_17080
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Tower+: Bridging Generality and Translation Specialization in Multilingual LLMs
Rei, Ricardo
Guerreiro, Nuno M.
Pombal, José
Alves, João
Teixeirinha, Pedro
Farajian, Amin
Martins, André F. T.
Computation and Language
Artificial Intelligence
Fine-tuning pretrained LLMs has been shown to be an effective strategy for reaching state-of-the-art performance on specific tasks like machine translation. However, this process of adaptation often implies sacrificing general-purpose capabilities, such as conversational reasoning and instruction-following, hampering the utility of the system in real-world applications that require a mixture of skills. In this paper, we introduce Tower+, a suite of models designed to deliver strong performance across both translation and multilingual general-purpose text capabilities. We achieve a Pareto frontier between translation specialization and multilingual general-purpose capabilities by introducing a novel training recipe that builds on Tower (Alves et al., 2024), comprising continued pretraining, supervised fine-tuning, preference optimization, and reinforcement learning with verifiable rewards. At each stage of training, we carefully generate and curate data to strengthen performance on translation as well as general-purpose tasks involving code generation, mathematics problem solving, and general instruction-following. We develop models at multiple scales: 2B, 9B, and 72B. Our smaller models often outperform larger general-purpose open-weight and proprietary LLMs (e.g., Llama 3.3 70B, GPT-4o). Our largest model delivers best-in-class translation performance for high-resource languages and top results in multilingual Arena Hard evaluations and in IF-MT, a benchmark we introduce for evaluating both translation and instruction-following. Our findings highlight that it is possible to rival frontier models in general capabilities, while optimizing for specific business domains, such as translation and localization.
title Tower+: Bridging Generality and Translation Specialization in Multilingual LLMs
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2506.17080