Ten Claude Opus 5.5 agents were tasked with finding a faster exact shortest-path algorithm for directed graphs with non-negative real weights and proving it correct in the Lean theorem prover. Over roughly 15 hours and 733 messages, the agents produced an algorithm called C-HD, which its creators say formally improves on previously published complexity bounds, including Dijkstra's algorithm and two recent 2025 and 2026 papers.
Anthropic launched a new AI model, Claude Opus 4.5, roughly ten days after its CEO publicly called for a slowdown in AI development. The company says the model performs well on internal alignment safety measures, while also stating that government policy will eventually be needed to guard against risks from AI systems that can improve themselves.
Anthropic released Opus 5.5, an update to Claude aimed at enterprise tasks like coding, financial analysis and business work, claiming better agentic coding benchmarks than GPT-6 Astra and reduced token pricing compared to Opus 5. OpenAI simultaneously released GPT-6 Sol and GPT-6 Luna, cheaper successors to GPT-5.6 that the company says cut factual errors roughly in half and match rival Fable 5.1's coding performance at lower cost.
OpenAI launched GPT-6 Sol and GPT-6 Luna, follow-ups to its 5.6 models and companions to the recently released GPT-6 Astra, aimed at giving businesses and developers Astra-level capability at lower cost with higher usage limits. Anthropic simultaneously released Claude Opus 5.5, which it says matches Fable 5.1's performance while cutting costs nearly 40% compared to Opus 5, and calls its most aligned model yet.
OpenAI added two new GPT-6 tiers, Sol and Luna, cutting API prices by 50% versus GPT-5.6 promotional rates, with Sol built for complex coding tasks and Luna aimed at high-volume document work. Anthropic released Claude Opus 5.5, a more token-efficient model it says costs about 40% less to run than Opus 5.
Anthropic's Claude Opus 5.5, running in Adaptive Reasoning Max Effort mode, scored 58 on the Artificial Analysis Intelligence Index against a median of 25 among comparable models. The model handles text and image input with text output and a 1M token context window, but is priced at $4.00 per 1M input tokens and $20.00 per 1M output tokens, both above the reported medians of $2.00 and $10.00. Evaluating it on the Intelligence Index generated 260M tokens and cost $8,708.20 in total.
Anthropic has released Claude Opus 5.5, an upgrade to its top-tier Opus model that arrives roughly two months after the previous version, in line with the company's usual release pace. The company says it performs close to its higher-end Fable/Mythos tier while being about 30% faster and 40% cheaper per task than Opus 5, with notable gains in large-scale coding work and software optimization tasks.
Anthropic released Opus 5.5, claiming it beats its larger Fable model on many coding and knowledge benchmarks while costing 20% less per output token and running faster. The model also communicates more plainly, avoiding jargon and leading with key information. Sonnet 5.5 and Haiku 5.5 are expected to follow in coming weeks with similar gains.
Anthropic released Claude Opus 5.5 less than two months after Opus 5, claiming performance near its top-tier Fable 5.1 model while running about 40% cheaper. The company says the model uses fewer tokens, produces less verbose answers without sacrificing accuracy, and generates output over 30% faster than its predecessor. Sonnet 5.5 and Haiku 5.5 versions are expected in coming weeks.
Anthropic released Claude Opus 5.5, the first entry in its 5.5 model family, matching the performance of Claude Fable 5.1 on most tasks while running 40% cheaper than its predecessor, Opus 5. The model underwent external evaluation by groups including Frontier Design and METR, and scored higher than any prior Anthropic model on the company's internal automated behavioral audit for alignment and safety.
Anthropic introduced Claude Opus 5.5, a cheaper, more efficient model that reroutes risky cybersecurity requests to the weaker Opus 4.8 and flagged biology queries to Opus 5. The company says it is the top performer on its internal alignment testing and was vetted by outside evaluators Frontier Design and METR before release.
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