> Purchasing a .open domain name isn't available to the general public. This particular extension is owned by American Express and currently isn't for sale or open to registration, limiting its use to only selected entities associated with American Express. It's primarily designed to serve the interests of the corporation and its customers' claims or needs.
This is a feature of arxiv that automatically converts text looks like a link into "this http url". The submitter missed the space after the "." in "...strong reasoning ability. OpenAI has claimed...".
whois says no, and it seems there's a close one of https://tld-list.com/tld/open that's owned by (strangely enough) American Express Travel. It could be yet another tpyo of foo.open.ai which would work today, no global TLD required (I mean, they have damn near unlimited money, just buy out whoever owns it now)
The correct URL is https://cdn.openai.com/o1-system-card-20241205.pdf , at least according to https://arxiv.org/html/2412.14135v1 (which contains typos that OP's submissions doesn’t).