  We introduce Eurus, a suite of large language models (LLMs) optimized for
reasoning. Finetuned from Mistral-7B and CodeLlama-70B, Eurus models achieve
state-of-the-art results among open-source models on a diverse set of
benchmarks covering mathematics, code generation, and logical reasoning
problems. Notably, Eurus-70B beats GPT-3.5 Turbo in reasoning through a
comprehensive benchmarking across 12 tests covering five tasks, and achieves a
33.3% pass@1 accuracy on LeetCode and 32.6% on TheoremQA, two challenging
benchmarks, substantially outperforming existing open-source models by margins
more than 13.3%. The strong performance of Eurus can be primarily attributed to
UltraInteract, our newly-curated large-scale, high-quality alignment dataset
specifically designed for complex reasoning tasks. UltraInteract can be used in
both supervised fine-tuning and preference learning. For each instruction, it
includes a preference tree consisting of (1) reasoning chains with diverse
planning strategies in a unified format, (2) multi-turn interaction
trajectories with the environment and the critique, and (3) pairwise data to
facilitate preference learning. UltraInteract allows us to conduct an in-depth
exploration of preference learning for reasoning tasks. Our investigation
reveals that some well-established preference learning algorithms may be less
suitable for reasoning tasks compared to their effectiveness in general
conversations. Inspired by this, we derive a novel reward modeling objective
which, together with UltraInteract, leads to a strong reward model.
