WORLDTECHAI
Fine-tuning GPT-OSS-20B for multilingual reasoning on Amazon SageMaker HyperPod
SFT took reasoning-language accuracy from 22% to 100%, and GRPO added measurable gains where headroom existed. The model receives a reasoning language: system-prompt instruction and must both reason and answer in that target language, overriding its strong English prior. GPT-OSS-20B is an open-weight (a model whose trained parameters anyone may download) (published so anyone may download the trained model) reasoning model that thinks in English. Ask it to reason in French, German, Spanish, or Italian and it acknowledges the instruction, then produces its chain-of-thought in English anyway. On a 50-example multilingual reasoning test, the base model reasoned in the correct target language only 22 percent of the time.
