Claude Sonnet 4.6 beats DeepSeek V4 Flash on rigor

Claude Sonnet 4.6 takes this head to head because its wins came on the tasks with the highest penalty for being almost right. In the Python cost allocation test, both models understood the shape of the solution, but DeepSeek used floating point arithmetic; that is a real robustness flaw for large integer inputs. Claude’s exact integer handling makes it the safer implementation. The meeting summary task was the clearest separation. Claude delivered the requested two sentence summary plus a com...