GPT-5.6 Is Now Available — Plus ChatGPT Work and a 50-Year Math Proof (July 2026)
July 11 update: GPT-5.6 Sol Ultra reportedly proved the Cycle Double Cover Conjecture — a 50-year-old math problem — using 64 parallel subagents in under an hour. Also covers the July 9 broad availability of GPT-5.6 Sol, Terra, and Luna across ChatGPT and the API, the launch of ChatGPT Work, and the original government-restricted preview.
So — which one should you buy?
July 11 update. OpenAI published a claim that GPT-5.6 Sol Ultra — using 64 parallel subagents — produced a proof of the Cycle Double Cover Conjecture, a 50-year-old unsolved math problem. The proof is machine-verified and publicly posted; peer review is pending. See the July 11 section below for what happened, what the caveats are, and what it means for professional work.
July 9 update. GPT-5.6 Sol, Terra, and Luna are now broadly available across ChatGPT, Codex, and the OpenAI API — 13 days after a government-restricted preview. OpenAI also launched ChatGPT Work, a new autonomous professional agent that completes tasks rather than just responding to prompts. GPT-5.6 is also now the preferred model in Microsoft 365 Copilot. The original June 26 post is preserved below; the new sections are at the top.
July 11, 2026: GPT-5.6 Sol Ultra produces a proof of a 50-year-old math problem
On July 10, 2026, OpenAI's Ethan Knight posted a striking claim: GPT-5.6 Sol Ultra had produced a proof of the Cycle Double Cover Conjecture — a graph theory problem posed independently by George Szekeres in 1973 and Paul Seymour in 1979 that had resisted proof for roughly half a century. OpenAI published the full proof and the complete prompt used to guide the system as public PDFs.
If the proof holds under peer review, it would be the most significant mathematical result ever attributed to an AI system.
What the conjecture asks
The Cycle Double Cover Conjecture asks a question that sounds almost simple: given any bridgeless graph (a network where no single edge, if removed, disconnects the graph), can you find a collection of cycles such that every edge appears in exactly two of those cycles?
That question has been open since the 1970s. It's not obscure — it sits in the published mathematical literature, with decades of partial results. No complete proof existed before this claim.
How Sol Ultra did it
This wasn't a single prompt. Sol Ultra's Ultra mode distributed the problem across 64 parallel subagents, each working simultaneously on different angles. The proof employed the 8-flow theorem and linear algebra over GF(3) — a finite field with three elements — a direction that existed in prior partial results. The full session completed in under an hour.
OpenAI posted both the proof PDF and the prompt PDF publicly, which is unusual transparency and allows independent verification.
The caveats — and why they matter
Mathematician Thomas Bloom reviewed the posted proof on X. His observations:
- The proof does not cite a foundational 1983 paper by Bermond, Jackson, and Jaeger that its approach builds on.
- The AI appears to have recombined existing mathematical results rather than constructed genuinely novel mathematics.
- The human prompt heavily constrained the approach — in Bloom's words: "One can imagine trying the natural labelling first ... while the AI does not get discouraged." The system's advantage may have been parallelism and persistence more than mathematical insight.
Most critically: the proof is machine-verified, not peer-reviewed. Machine verification confirms that the logical steps are internally consistent. Peer review is the process where human mathematicians read the proof, check whether it's complete, look for subtle gaps, and confirm they understand why it works — not just that the steps don't contradict each other. The Cycle Double Cover Conjecture has attracted prior claimed proofs that were later found to have errors. Independent verification takes time.
What this means for professional work
The direct practical implication for most professionals isn't "AI can now do math I can't." It's more specific:
Ultra mode is built for parallel, structured search. The architecture that produced this proof — many parallel agents, each pursuing a different angle of the same hard problem simultaneously — is the same architecture available to you when you use Sol Ultra for complex, multi-strand tasks. Legal research across conflicting precedents, regulatory compliance across large document sets, financial analysis over large data: these share the same "parallel structured search" shape.
The AI reasoning ceiling just moved. If Sol Ultra can navigate 50 years of graph theory literature and produce a logically coherent proof in under an hour, the upper bound of what AI-assisted analysis can reach is higher than it was last week. The implication for everyday professional work isn't dramatic — this was an extreme case — but it shifts what's plausible.
Verification remains your responsibility. The math community is scrutinizing this proof carefully, and they're right to. Machine-verified is not peer-verified. The same discipline applies to AI-assisted work in your field: treat AI output as a strong starting point, not a final answer, and apply domain judgment before you act on it.
This is a significant data point about where AI reasoning currently stands. Whether the proof survives peer review determines how significant.
July 9, 2026: GPT-5.6 is broadly available
After a 13-day restricted preview, OpenAI opened GPT-5.6 to all users on July 9, 2026. The rollout is happening over 24 hours across ChatGPT, Codex, and the OpenAI API.
What you get by plan:
| Plan | Model access |
|---|---|
| Free / Go | GPT-5.5 (GPT-5.6 Terra on Codex and ChatGPT Work surfaces) |
| Plus / Business | Sol, Terra, or Luna (adjustable effort) |
| Pro / Enterprise | Sol, Terra, or Luna + Ultra mode |
The pricing table from the original June 26 announcement holds — no changes:
| Model | Best for | API pricing (input/output per 1M tokens) |
|---|---|---|
| Sol | Complex agentic work, coding, research | $5 / $30 |
| Terra | Balanced everyday professional use | $2.50 / $15 |
| Luna | Fast, high-volume, affordable tasks | $1 / $6 |
For most professionals, Terra is the practical everyday model — it replaced GPT-5.5 Instant as the default for free users and sits at the same price tier. Sol is the headline flagship, but its pricing positions it for use cases where output quality justifiably costs more — complex analysis, multi-step agentic tasks, research with high stakes for accuracy.
GPT-5.6 is also now the preferred model in Microsoft 365 Copilot. OpenAI announced on July 9 that GPT-5.6 replaces GPT-5.5 across Outlook, Teams, Word, Excel, and other Copilot surfaces. If your organization uses M365 Copilot, the upgrade is automatic — no subscription change required.
ChatGPT Work: what it is and who it's for
The bigger change on July 9 isn't the model — it's a new product: ChatGPT Work.
Where regular ChatGPT responds to your prompt, ChatGPT Work takes a goal, gathers context from your connected apps, and executes tasks autonomously — returning a finished artifact rather than a conversation. Think of it as the difference between "tell me how to write a monthly report" and "here is the monthly report, compiled from your CRM and email."
Specific tasks the agent is designed for:
- Lead triage and pipeline analysis across CRM, call recordings, and email
- Competitor research and benchmarking (compressed from days to hours)
- Monthly reporting and deck assembly from live data sources
- Event preparation and readiness tracking
- Scheduled recurring workflows that update as underlying data changes
A few design choices worth knowing:
Plan mode shows you the execution steps before the agent acts — useful if you want to approve the approach before it runs. This is the default for new task types.
Auto-review is a built-in safety layer that blocks attempts to extract data outside your connected apps. It doesn't require configuration.
Scheduled tasks mean you can set recurring workflows — "send me a pipeline summary every Monday at 8am" — without manual triggering.
Pricing is metered, not flat. OpenAI hasn't published per-task prices; actual cost scales with task complexity and tool calls. OpenAI recommends running pilot tasks before scheduling high-frequency recurring workflows, to measure real consumption.
Availability right now:
| Surface | Available when? |
|---|---|
| macOS desktop — all plans | July 9 (immediate) |
| Windows desktop | Rolling out over following days |
| Web & mobile — Pro, Enterprise, Edu | July 9 (immediate) |
| Web & mobile — Plus, Business | Within days of July 9 |
ChatGPT Work uses GPT-5.6 as its underlying model. Ultra mode (parallel sub-agents for demanding work) is available to Pro and Enterprise subscribers.
How ChatGPT Work relates to Claude Cowork. These products are now the closest direct competitors in the professional AI space. Both execute multi-step tasks autonomously; both support scheduled workflows and integrations. The key structural difference: ChatGPT Work runs in the cloud (tasks continue even when you close the app), while Claude Cowork runs on your desktop (with local file access and deeper system integration). Both support plugin ecosystems — OpenAI cites 1,400+ integrations; Claude Cowork's Skills system covers profession-specific workflows. If your daily work already lives in OpenAI's ecosystem (M365 Copilot, ChatGPT Business), ChatGPT Work is the natural fit. If you rely on local files, Claude tools, or profession-specific packaged workflows, Cowork has the edge. Neither is universally better — they're shaped for different working environments.
Original post (June 26, 2026)
The content below was written at the time of the restricted launch. The model is now broadly available; see the July 9 sections above for the current state.
Original TL;DR (June 26). OpenAI launched GPT-5.6 Sol on June 26, 2026 — its most capable model yet. But the Trump administration asked OpenAI to limit access to ~20 government-approved partners pending safety review. Regular ChatGPT and API users didn't have access at that time. Broader rollout was expected in coming weeks — and arrived on July 9.
What happened (June 26)
On June 26, 2026, OpenAI announced the GPT-5.6 model family: Sol (flagship), Terra (balanced), and Luna (fast and affordable). By most benchmark measures, Sol is OpenAI's strongest model to date — scoring 88.8% on Terminal-Bench 2.1 for agentic coding, and showing notable improvements in biology and cybersecurity tasks.
At the request of the Trump administration, OpenAI limited the initial rollout to a small group of government-approved "trusted partners" — approximately 20 companies whose participation required individual government sign-off. For everyone else — ChatGPT subscribers, API users, developers — access was unavailable at launch.
Why the government got involved
The US government's involvement with frontier AI releases escalated quickly in 2026. In June, the Trump administration issued an export control directive that forced Anthropic to take Claude Fable 5 and Mythos 5 completely offline — a full global suspension lasting 19 days. (For the full story, see our post on Claude Fable 5.)
With GPT-5.6, the approach was different but the pattern was the same: the government inserted itself into the release process before models reached the public. Rather than a post-launch ban, the administration asked for a pre-release review period with a vetted partner group.
OpenAI's public statement at the time: "We don't believe this kind of government access process should become the long-term default." They complied, but signaled opposition to this becoming standard practice.
TechCrunch's analysis captured the shift: this situation was no longer about Anthropic vs. OpenAI. Both companies faced identical regulatory pressures from the same government. Both are now working with the White House and Commerce Department to establish a more repeatable framework for future model releases.
The bigger picture (still relevant)
What happened with GPT-5.6 wasn't isolated. It was the second major frontier model release in two weeks caught in US government review — following the Fable 5 suspension on June 12. Both resolved within July, but the pattern remains: the Trump administration is treating frontier AI models as regulated technology requiring government sign-off, and that precedent doesn't disappear just because both models are now available.
For professionals, the practical takeaway: the tools you have are sufficient for the work you need to do. The frontier models will arrive — and with GPT-5.6 now broadly available, the current question is which tool fits your workflow, not when it will show up.
Sources
July 11, 2026 update:
- A Proof of the Cycle Double Cover Conjecture (PDF) — OpenAI, July 10, 2026 (primary source: the proof itself)
- Prompt used for the proof (PDF) — OpenAI, July 10, 2026 (full prompt published alongside the proof)
- OpenAI's GPT-5.6 Sol Ultra reportedly solves a 50-year-old math problem in under an hour — The Decoder, July 11, 2026
- OpenAI's GPT-5.6 Sol Ultra proves 50-year-old math conjecture in under an hour — CryptoBriefing, July 10, 2026
- GPT-5.6 Sol Ultra produces proof of the Cycle Double Cover Conjecture — Hacker News discussion — Hacker News, July 2026 (mathematician peer discussion including Thomas Bloom's analysis)
July 9, 2026 update:
- OpenAI unveils ChatGPT Work agent, GPT-5.6 models now available — 9to5Mac, July 9, 2026
- OpenAI Launches GPT-5.6 and ChatGPT Work AI Agent — Forbes, July 9, 2026
- OpenAI's GPT-5.6 and ChatGPT Work aim to beat Anthropic on price, speed, and productivity — ZDNet, July 9, 2026
- ChatGPT Work: OpenAI's Agent That Ships Finished Work — DigitalApplied, July 9, 2026
- GPT-5.6 is now the preferred model in Microsoft 365 Copilot — OpenAI, July 9, 2026
- OpenAI releases latest ChatGPT model after delay over White House cybersecurity concerns — The Guardian, July 9, 2026
Original June 26, 2026 sources:
- OpenAI limits GPT-5.6 rollout after government request, says restrictions shouldn't be the norm — TechCrunch, June 26, 2026
- OpenAI's Claude Mythos competitor GPT-5.6 Sol launches under government-controlled access it calls unsustainable — The Decoder, June 26, 2026
- OpenAI releases GPT-5.6 Sol to 20 government-approved partners in restricted preview — The Next Web, June 26, 2026
- OpenAI releases powerful new GPT-5.6 model under restrictions — Axios, June 26, 2026
- It's not about Anthropic vs. OpenAI anymore — TechCrunch, June 26, 2026
So — which one should you buy?
Frequently asked questions
Is GPT-5.6 available right now?+
Yes. GPT-5.6 Sol, Terra, and Luna became broadly available on July 9, 2026, rolling out across ChatGPT, Codex, and the OpenAI API over 24 hours. Free accounts remain on GPT-5.5 (Go gets expanded GPT-5.5 access). Plus, Pro, Business, and Enterprise users can choose among Sol, Terra, and Luna with adjustable effort levels. Pro and Enterprise users can additionally access Ultra mode, which distributes complex tasks across parallel sub-agents.
What is GPT-5.6 Sol?+
GPT-5.6 Sol is OpenAI's newest flagship model, first announced in restricted preview on June 26, 2026, and broadly available from July 9. It is the top tier of a three-model family — Sol (flagship), Terra (balanced everyday use), and Luna (fast and low-cost). Sol features improved agentic capabilities in coding, biology, and cybersecurity, and introduces 'max' and 'ultra' reasoning modes. Ultra can distribute complex tasks across parallel sub-agents. OpenAI says Sol achieves 88.8% on the Terminal-Bench 2.1 coding benchmark.
What is ChatGPT Work?+
ChatGPT Work is OpenAI's new autonomous task agent, launched July 9, 2026. Unlike regular ChatGPT (which responds to prompts), ChatGPT Work takes an outcome, gathers information across your connected apps and files, and completes tasks independently — delivering finished artifacts like spreadsheets, slides, reports, websites, and documents. It supports Plan mode (step-by-step approval before execution), scheduled recurring tasks, and 1,400+ plugin integrations. Pricing is metered by task complexity rather than a flat subscription. macOS desktop availability started immediately for all plans; web and mobile are rolling out to Plus and Business within days.
What are Sol, Terra, and Luna — and what do they cost?+
All three are part of the GPT-5.6 generation. Sol is the flagship (most capable, $5 per million input tokens / $30 per million output tokens via API). Terra is balanced for everyday professional use ($2.50/$15 per million). Luna is the fast, affordable option ($1/$6 per million). All three are now broadly available through ChatGPT and the OpenAI API as of July 9, 2026.
Why was GPT-5.6 restricted when it first launched?+
The Trump administration asked OpenAI to limit the initial June 26 rollout to approximately 20 government-approved 'trusted partners' pending additional safety review. OpenAI complied but publicly objected: 'We don't believe this kind of government access process should become the long-term default.' Following a 13-day restricted review period, GPT-5.6 was cleared for broad release on July 9, 2026.
How does this compare to what happened with Claude Fable 5?+
The mechanisms were different in severity. The US government issued an export control directive in June 2026 that forced Anthropic to take Claude Fable 5 completely offline globally — a full suspension lasting 19 days. The GPT-5.6 restriction was a limited rollout to ~20 approved partners, not a shutdown. Both are now resolved: GPT-5.6 is broadly available (July 9), and Claude Fable 5 was restored globally on July 1. Both situations reflected the same pattern of government involvement in frontier model releases.
Is GPT-5.6 now the model in Microsoft 365 Copilot?+
Yes. OpenAI announced on July 9, 2026 that GPT-5.6 is now the preferred model powering Microsoft 365 Copilot, replacing GPT-5.5 as the default in Outlook, Teams, Word, Excel, and other Copilot surfaces. This means M365 Copilot users get the newer model without a separate subscription change.
Is the government's approval process here to stay?+
OpenAI explicitly says it hopes not. Their statement: 'We don't believe this kind of government access process should become the long-term default.' Both OpenAI and Anthropic are now working with the White House and Commerce Department to develop a repeatable framework for future model releases — one that could be more predictable and less ad-hoc. As TechCrunch noted, the situation has shifted the conversation from Anthropic-vs-OpenAI competition to both companies facing the same regulatory challenge.
Did GPT-5.6 Sol Ultra really solve a 50-year-old math problem?+
On July 10, 2026, OpenAI published a claim that GPT-5.6 Sol Ultra produced a proof of the Cycle Double Cover Conjecture — a graph theory problem posed independently in 1973 and 1979 that had resisted proof for about 50 years. The system used Sol Ultra's 'Ultra mode,' which runs 64 parallel subagents simultaneously, completing the proof in under an hour. OpenAI released the full proof and prompt as public PDFs. Mathematician Thomas Bloom reviewed the proof on X and raised concerns: a foundational 1983 paper was not cited, and the AI appears to have recombined existing mathematical results rather than discovered genuinely novel mathematics. The proof is machine-verified (its logical steps check out) but has not been peer-reviewed — a significant distinction. Peer review is where human mathematicians evaluate whether the proof is correct, complete, and comprehensible. The result is a serious claim worth watching; whether it holds up under peer scrutiny determines whether it's a milestone.
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