fable

Fable 5 helps disprove a nearly century-old conjecture

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While Spain made history winning his second soccer World Cup on Sunday, a 34-year-old Harvard mathematician named Levent Alpöge asked Fable 5 for something interesting. Not that he tried to prove the Jacobi conjecture, but that he did the opposite: to refute it. Argentina kicked us while Spain played soccer and Ferrán of my life and my heart scored a historic goal. By the time it was all over, two things happened. The first, that Spain, we insist, was making history with its second star on the shirt. The second, that a conjecture that had not been proven for almost 90 years was definitively refuted thanks to the help of an AI. The aforementioned Jacobi conjecture suggests that a certain type of mathematical function could also work in reverse. It was formulated by Ott-Heinrich Keller in 1939, and in 1998 the mathematician Stephen Smale included it in his famous list of unsolved mathematical problems that were a challenge for mathematicians of the 21st century. A discovery that leaves as many questions as answers Alpöge has not explained in detail how he managed to reach that result or what prompt he used, but in his tweet he indicated that part of the credit was due to his “close friend fable“, the Anthropic model. Abhishek Sahafrom Queen Mary University of London, explained that the very way of facing the problem was unexpected. The conjecture seemed intuitively correct, but no one was trying to refute it, but rather prove it. Chris Bowman-Scargillfrom the University of York, pointed out something that he considers very important: it is one thing to find counterexamples that overturn conjectures and quite another to construct entire branches of mathematicswhich still requires human creativity. He gave as an example Fermat’s last theorem, solved by Andrew Wiles in 1994, and which forced him to develop dozens of pages with new and fascinating mathematical theories. Several experts have already validated this refutation, something that was relatively easy to do. For Saha, AI advances in mathematics had already surprised —they did it with one of the problems recently—, but this went further: “It is probably the most important conjecture in which AI has played a relevant role so far in mathematics,” he said. There is however some open questions: This particular counterexample refutes the conjecture with three variables, but a version with only two variables could be true. One thing is certain: mathematicians are taking advantage of this tool to help them in their work. The most famous in the world does it, of course. Ivan Fesenkofrom Westlake University in China, was talking about this when he stated that AI models are becoming more and more capable: “Right now, AI can already produce math graduates. In a year, it will produce math PhDs. And then the question arises: Do we really need that many mathematicians if AI can do these things so well?” It is a disturbing question, of course. Image | Vitaly Gariev In Xataka | A mathematical problem had been resisting experts for more than 80 years. An AI has surpassed them all

Fable 5 is back with small print. One that says who really rules in US AI

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Fables 5 has returned three weeks after the US government ordered its blackout. It returns with several asterisks: it only allows 50% of weekly usage for paid plans, and it brings a more aggressive security filter along with a commitment that binds Anthropic to share with the government every model that comes after it, including future ones. The official origin is a reproducible failure in models much inferior to Fable. But what remains after solving it weighs more: early government access before each launch and dedicated computing to audit the models. In detail. On June 12, the US government acted after learning of a report from Amazon researchers that Fable 5 had identified software vulnerabilities by bypassing its safeguards. Anthropic replicated the finding with less powerful models (Opus 4.8, GPT-5.5 and Kimi K2.7) and everyone got it the same. On June 30, the restriction was lifted. Of course, the new classifier notifies the user when it blocks a request and redirects it to Opus 4.8. Between the lines. Anthropic admits that this classifier blocks more harmless requests, especially in programming and debugging code, its main use. The safety margin itself, the company says, is “far greater than in any previous release.” Alberto Romero, in The Algorithmic Bridgereads it like this: if the model fails due to excess caution in its most common use, the real ceiling of what a user can squeeze out remains at the level of Opus 4.8 either GPT-5.5although the model below is more powerful. Why is it important. Anthropic grants early access to models that “materially advance the capability frontier” in national security, and assembles internal teams for government priorities. The government reserves the right to reimpose the license “if circumstances change”, but without defining which ones. Since the premise of this industry is that a larger model develops new capabilities overnight, almost any advancement fits that phrase. The context. Anthropic has been collaborating on an ad hoc basis with US agencies such as the Treasury and the National Cybersecurity Office for almost two years. What is new is that this work becomes a permanent protocol, and that Fable and Mythos They are the first to pass through it. Anthropic has been chasing OpenAI for years, but in 2026 it has taken the lead on several fronts, in the heat of Claude Code, Claude Cowork and the discovery of the quality of their models’ responses by those who had not left ChatGPT. Accepting this tutelage now, when they finally have something to lose, is a gamble: they prefer a guarded border to a race that neither they nor their government fully control. And now what. What needs to be monitored is whether the classifier improves its accuracy in code without losing a strong hand, and whether OpenAI or Google end up signing something similar. If that happens, Fable’s return will no longer seem like an isolated incident. In Xataka | Sharing your ChatGPT or Claude password is not like sharing your Netflix password: there are people learning it the hard way Featured image | Anthropic

We believed that no Chinese AI model would soon come close to Fable 5 or GPT-5.5. Then GLM-5.2 arrived

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A few days ago, the Chinese startup Zhipu AI (Z.ai) announced the launch of its new open AI model, GLM-5.2. It did so boasting amazing features that brought it very close to the best closed models from OpenAI and Anthropic, something that seemed impossible. Well, the more analysis is carried out on the model, the better off it is. We may be at the beginning of something very important. A change of trend. GLM 5.2. The Chinese startup Z.ai has been releasing different versions of its GLM AI model for a long time, but the latest one is undoubtedly the most surprising because its performance is especially promising. It has 744,000 million parameters (744B), of which 40,000 are those that remain active. We are looking at a model with a context window of one million tokens and a new architecture called IndexShare/IndexCache. Better than GPT-5.5, very close to Opus 4.8. The startup showed how the performance of GLM-5.2 is extraordinary in programming tasks. In the FrontierSWE test, the most demanding of those currently available, GLM-5.2 outperformed GPT-5.5 and only Opus 4.8 was superior by a very small margin. The same happened with other tests such as PostTrainBench or SWE-Marathon, which, for example, evaluates the behavior of the model in very long autonomous programming sessions. Source: Z.ai. In many other tests the photo was identical: the model has made a spectacular leap since version 5.1, and is in many tests almost as good (or better) than the best from OpenAI, Anthropic or Google. But it’s not just them who say it.. Artificial Analysis, a reputable independent firm that maintains an updated ranking of the performance of the new AI models that are arriving on the market, confirms the data of Z.ai itself. In his tests he indicates how the “intelligence index” of GLM-5.2 is now 51 points. It is only surpassed by GPT-5.5 (55), Claude Opus 4.8 (56) and Claude Fable 5 (60). Source: Artificial Analysis. This Chinese open model leaves behind the new Gemini 3.5 Flash, but also Chinese competitors such as Qwen 3.7 Max, MiniMax-M3 or DeepSeek V4, among others. The jump in quality from GLM-5.1 is, we insist, outstanding, much greater than what, at least according to this index, was seen from Opus 4.8 to Fable 5. The jump in performance is spectacular, although it is true that the comparative price to solve the tasks proposed in the benchmark rises significantly. Source: Artificial Analysis. But it’s not perfect. The Artificial Analysis report, however, shows that although GLM-5.2 is very strong in areas such as programming, it is weak in others. For example, it is far from being as reliable as Fable 5, GPT-5.5, Claude 4.8 or Gemini 3.1 Pro in terms of correct answers, which is also lower in proportion to that of its competitors. However, his hallucinations have significantly reduced. And it’s much (much) cheaper. But in addition to being fantastic in many areas, it is much cheaper than its competitors. Maintains the price per million input/output tokens of its predecessor ($1.4/4.4), while that of GPT-5.5 It’s 5/30 dollars and that of Opus 4.8 10/50 dollars. It is true that it consumes many more tokens than GPT-5.5 (very efficient) or Claude Opus 4.8, but even with that its final cost is much lower. My tests with GLM-5.2 programming. I’ve been a Z.ai subscriber for months now because they offered an annual subscription at the end of 2025 at a really low price. This has allowed me to test GLM-5.2 for a few hours and although I cannot draw definitive conclusions, it does seem clear that there is a leap in quality in terms of its ability to program. I asked him to review a personal code project and he identified several security flaws and possible improvements in great detail. Chatting with GLM5-2. In conversational mode the behavior is much more difficult to evaluate: I have been interacting with the model and asking it questions, and although it is better than GLM 5.1 many times, other times it is not so much and I would say that in terms of creativity to write the frontier models of Google, OpenAI and especially Anthropic they are still quite superior. You can try it on their websiteand there you will see something else: it takes significantly longer to respond than other chatbots, because its reasoning phase is longer. Take more time to answer questions. Benchmarks are one thing, experience is another.. In the absence of testing it (much) more, of course the impression is that the model has improved significantly compared to a GLM-5.1 that had lagged behind its Chinese competitors (not to mention the current Claude Opus 4.8 or GPT-5.5). On platforms like Reddit opinions are dividedbut many consider it a fantastic option to run locally… if you have a very, very powerful machine with at least 256 GB of unified memory (Mac Studio). And one thing seems clear: when using it as an AI model for programming, comes surprisingly close to Claude Opus 4.8. In Xataka | Chinese technology companies entered the AI ​​race with cheaper models than the rest. That’s starting to end

The United States presses the fear button with Claude Mythos and Fable 5. It is a blackout with a clear beneficiary: China

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The United States has turned off the tap most powerful, expensive and advanced AI model ever released by Anthropic, but it has done so in a disconcerting move and with small print. Yesterday, June 12, the White House ordered Anthropic to immediately shut down Fable 5 and Mythos 5 for anyone who is not a US citizen. The order arrived without giving too many explanations about its duration or technical justification, according to Anthropic’s public statement. This government intervention marks a before and after in the modern technology sector: they are not restricting the sale of chips (a common practice), but vetoing access to general access software as a matter of national cybersecurity. What’s happening with Fable 5 and Mythos 5. The US government has issued an export control directive suspending all access to Fable 5 and Mythos 5 for anyone who does not have US citizenship, whether inside or outside the United States. This includes non-U.S. Anthropic personnel. In order to adhere to the directive that came into effect immediately, the company led by Dario Amodei has had to deactivate both models for everyone. At the time of publishing this article, the notice appears when trying to access it. According to Anthropic, the government believes it has discovered a way to jailbreak the model. The company does not agree: after reviewing the demo of this technique to deceive the model, it concludes that the vulnerabilities found are minor, were already located and applicable to other models on the market and can be identified without the need for any circumvention technique. What you see right now if you enter Claude Why is it important. Because Mythos It is a specifically designed model for cybersecurity and its blackout affects both commercial users and those entities in charge of active defense management that are using it. With this measure, Washington turns its cutting-edge AI software into a national security asset. It is worth remembering that Anthropic is already on the blacklist of the Pentagon, so he considers it too dangerous for his Government to use. It is also now too dangerous for foreigners to use. Besides, as Anthropic points outsets a dangerous precedent: if the criterion for withdrawing a model is that someone finds a vulnerability, in practice none will be able to be launched because the company that releases software without a single failure raises its hand. That is to say, if the White House makes this exceptional movement the norm, it will be a shot in the foot to develop cutting-edge models: slower launches due to this “impossible” debugging process, personnel decimated by not being able to count on foreign specialists and if they cannot be marketed abroad there will be less income. Context. This order is the latest chapter in a soap opera of disagreements between Washington and Anthropic that dates back to the beginning of the year. In March, the Pentagon considered that the company was a “supply chain risk.” In its statement, Anthropic has verified that that level of capacity that the government identified as dangerous in Fable 5 is already available in other models on the market, including the GPT-5.5 by OpenAIearlier and more widespread than Mythos. However, that version of ChatGPT has not suffered any suspension. The asymmetry of treatment between OpenAI and Anthropic is evident. The geopolitical context is also important: the United States and China are immersed in a technological race unprecedented in recent decades and each power is playing its weapons, from tariffs to critical materials like rare earths to vetoes on chip sales, EDA software or the Export Control Reform Act 2018, where new technological categories fit, such as the most advanced AI models. Of course, for the Asian giant, every obstacle has worked as a kind of catalyst to advance faster and be increasingly independent of outside technologies. In detail. The order’s enforcement mechanism is supported by the “export control directive” managed by the Department of Commerce. In practice, it means that accessing Fable 5 or Mythos 5 as a foreign citizen (even if you are in the United States) is grounds for infringement. Anthropic tried to anticipate the problem with thousands of hours of testing with the US government, shared it with 40 organizations that manage critical infrastructure and then, with another 150 entities more precisely so that they could find and thus be able to correct vulnerabilities before a third party with malicious interests did so later. It hasn’t been enough. Because Mythos It is a specifically designed model for cybersecurity. Before its public deployment, Anthropic shared it with organizations that manage critical infrastructure precisely so that they could find and thus be able to correct vulnerabilities before a third party with malicious interests did so. Its blackout affects both commercial users and those entities in charge of active defense management. Yes, but. For now, Anthropic complies with the order, but makes it clear that it does not agree and that it is working to resolve it: “We believe this is a misunderstanding and we are working to restore access as soon as possible.” The company behind Claude says it supports the government in blocking really dangerous technologies, but that this process has to be transparent, fair and based on real technical facts. In short, he has not said the last word. On the other hand, the million-dollar question is whether the US government can apply the export control law, initially designed for chips, satellites or critical and specific software, on an AI model available on the internet and in general use. In fact, this regulatory movement puts on the table the importance of having a clear law that defines when, how and with what guarantees a government (in this case, the United States) can intervene. In Xataka | Spain does not want to wait for Mythos to wreak havoc on its companies: that is why it is going to ask for “early access” to Anthropic In Xataka | Claude Fable 5 is the most powerful public … Read more

Claude Fable 5 is the most powerful public AI model in history. Also the most expensive, exclusive and frustrating

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When Anthropic presented Claude Mythos Preview two months ago, he did it with a singular message: it is so powerful that you will not be able to use it. That, of course, caused everyone to want access to it. Well: Anthropic has just introduce Claude Fable 5 and Claude Mythos 5its new AI models directly derived from that. There is good news, but also bad news. Like Mythos, but capped as a precaution. Anthropic already warned that Claude Mythos Preview was a spectacular tool for finding security vulnerabilities. That made it especially juicy for cybercriminals, so the company decided that only a few trusted entities (under its Project Glasswing) would have access to the model. That learning has now been applied, because in this announcement we have two different (and layered) versions of the model: Claude Fable 5: a model with all the capabilities of Mythos Preview, but with notable security measures that prevent it from being used for malicious purposes. As soon as the model detects that we are asking something “dangerous”, it avoids the question and even forces the use of an inferior model, Claude Opus 4.8. Clear examples: questions about cybersecurity or the development of biological weapons, for example. Claude Mythos 5: This version is somewhat less capable than Fable 5 in terms of cybersecurity, but will only be available to “a small group of cyber defenders and infrastructure providers.” It is the natural heir to Mythos Preview, and according to its creators it is even better than the original version. Claude Fable 5 / Mythos 5 simply sweeps the most demanding benchmarks on the planet. There have never been more powerful models. Anthropic’s internal testing shows that we are facing the most powerful AI models in history. In all benchmarks – including the new FrontierCode programming, much more demanding than SWE Bench Pro – the scores of Claude Fable 5 and Mythos 5 are simply spectacular, well above those of their rivals. The jump from Claude Opus 4.8 is really surprising, but it leaves GPT-5.5 and Gemini 3.1 Pro far behind (they don’t compare with the recent 3.5 Flash). This is a brutal blow to Anthropic’s table, and we will see how both OpenAI and Google respond. Claude Fable 5 is amazing. Ethan Mollick, well-known AI popularizer, has had access to Fable 5 for a few days and is amazed by the experience. With this model he has managed to complete projects such as east of the isochronic map that previous models had never solved, and it has done it almost “the first time”. In one of the cases Fable 5 worked for 9 and a half hours straight to produce a code called Concord of data analysis. Their conclusions are compelling: Last year (when working with GPT-5 Pro) I called him “work with a magician”: you recite the spell and something happens. With Fable, the spell has become so powerful that I’m no longer sure I’m the wizard. I feel more like a patron. I describe what I want, pay for it and evaluate the result. The conspiracy takes place somewhere I can’t see, in hundreds of small decisions over which I never have a say. Work has gone from being a process to being a result. I no longer direct; charge. The criticism is unanimous. Andrej Karpathy, who recently signed by Anthropic, commented on X how this is a qualitative leap that for him is of the same relevance as the one that Claude 4.5 represented in November. That model began the overtaking of OpenAI: this puts it even further away (at least, for now). Other tweetersemployees or not from Anthropic, make it clear that this is an important leap in the capabilities of AI models. It’s only been a few hours since the launch, but everything points because we are indeed facing a notable leap in quality. Consume tokens like there’s no tomorrow. But in the face of that fascination, the criticism. Discussions on Reddit reveal how users who have started using it have quickly detected the problems associated with this release. The first of them: Claude Fable 5 burns tokens like there is no tomorrow. Its consumption is enormous, and the quotas for Pro and even Max accounts run out in minutes if we use the model intensively. If it already seemed to us that we were exhausting the limits of the free or quick payment accounts, with Claude Fable 5 that feeling worsens: Fable 5 is fantastic, but we can barely use it often with the Pro or Max plans because those dreaded messages about waiting X hours to continue using it quickly appear. Extremely cautious. Anthropic has been very serious about avoiding misuse of Fable 5, and as soon as it detects anything suspicious it “brakes” and “downgrades” the model so that at that moment the one that is activated is Claude Opus 4.8 (which is not bad at all). The problem is that users are detecting that the model takes completely harmless prompts as dangerous. Although in Anthropic indicate Although these security measures are activated in less than 5% of sessions, what users are detecting is that they are activated much more. Fable 5 can get silly. Not only that: Fable 5’s own design means that if it encounters a prompt that it detects as dangerous, the model tries to avoid the response and automatically reduces your capabilities (‘nerfing’) without you knowing. It gets a little sillier on purpose, so to speak. As Anthropic itself explains on the system card, We have implemented new measures that limit Claude’s effectiveness in requests related to the development of cutting-edge large-scale language models (LLMs) (for example, in creating pre-training pipelines, distributed training infrastructure, or designing machine learning accelerators). Using Claude to develop competing models already violates our Terms of Service, but enforcing this restriction through our security measures prevents giving an advantage to those users most willing to violate those terms. Unlike our cybersecurity, biology and chemistry interventions, and distillation attempts, … Read more

The box office did not treat it well, but this stimulating apocalyptic fable now reaches prime video and it is worth recovering it

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There are those who tire postapocalyptic films with arbitrary rules that must be met to survive. Do not make noise. Don’t look. Don’t talk. Do not move. And in ‘You never release‘, that now premiere prime videothe rule is clear from the first moment: do not stop grabbing your classmates, do not stay alone, or get on the way. However, this proposal starts from that point to go in a very dike direction A manido start, yes, but effective and reserves a good amount of surprises. Everything fits that in command of this party we have Alexandre Aja, the Frenchman who terrified us at the beginning of his career with the extraordinary remake of ‘Las Colinas has eyes’, and that he has then developed a career full of ups and downs, yes, but With pieces of pure horror as estimated as ‘high voltage’, ‘Piraña 3D’, ‘Hell underwater’ or ‘oxygen’. On this occasion, Aja presents us with two twin children who live sections in a cabin in the depth of the forest with his mother (Halle Berry), which tells them about a dangerous spirit that lives abroad. To survive they must always be together, even tied by strings. It is a measure that will begin to question according to children are growing and suspect that the world does not work as they have told them. Mental illnesses, traumas and overprotection are some of the ingredients of this tense story not exactly apocalyptic (although moods are very there). Full of macabre details that certify the good visual taste of AJA, ‘You never let go’, unfortunately, it was received very timidly at the box officeand raised only 21.8 million dollars compared to the already lean 20 that had a budget. It is time to recover it and give it a new opportunity. In Xataka | ‘Oxygen’: a science fiction thriller of Netflix and Alexandre Aja (‘High voltage’) in which surprises and claustrophobia abound

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