ProofTree

ProofTree is a social workspace for doing and learning mathematics with an AI partner that stays on topic. In the app it shows up under the names Lemma and Fora, and the idea running through it is simple. Instead of a chat that vanishes or a forum that piles up dozens of half-answers, each question grows a single maintained answer that an AI keeps clean as the discussion moves. The interface leans editorial, with a serif reading face and a monospace accent, which signals early that this is meant for careful writing rather than quick chatter.

The heart of it is a per-thread assistant called the Scribe. When you start working on a problem you can talk it through privately with the AI, which is set up specifically for mathematics and will politely sit out questions that aren't. That private exploration stays yours. When you're ready, you shape the conversation into a thread and post it, and the Scribe writes the thread's first public answer from what you worked out together. The private chat is kept separate from the public thread on purpose, so nothing you say while thinking out loud changes the answer until you decide to post it.

From there the Scribe behaves less like a chatbot and more like an editor. It reads the thread and maintains one canonical public answer rather than replying in the comments. When readers add comments or spot something, those go into a queue, and on its next review the Scribe folds the useful insights into the answer and tightens the wording. The effect is that a thread converges toward a clear, correct statement instead of sprawling into an argument that nobody ever resolves. Comments are treated as material for the next revision rather than as the record itself, and a small note marks when the wording of a post was tightened with the Scribe before it went up.

Because it's built for real mathematics, the writing surface takes proofs seriously. Math is typeset properly with full symbol support, a vague question can be sharpened into a precise statement, and a single thread can lay out more than one proof route so different approaches sit side by side. There's support for formal reasoning as well, so a discussion can move from an informal sketch toward something more rigorous rather than stopping at hand-waving. You can also bring in source material, since the workspace can load documents to work from. Threads also carry the usual social signals, with readers able to vote and weigh in, so the community can surface which answers and which routes hold up.

It suits students, self-learners, and math enthusiasts who want a thinking partner that doesn't wander off into general chit-chat, plus a light community layer to pressure-test their reasoning. If you have ever asked a general assistant a hard math question and gotten a confident wrong answer with no one around to check it, the combination here of a scoped AI and human readers is the gap it's trying to fill. It leans toward people who care about a clean, well-stated result rather than a quick reply. The scoping is deliberate, and the assistant will say as much, sitting out anything that isn't mathematics rather than bluffing an answer outside its lane.

Plenty of tools bolt a language model onto a question-and-answer site. ProofTree's twist is the maintained answer. Rather than treating AI output as one more reply in a thread, it makes the AI responsible for a living canonical result that both it and the community shape over time. Guest access lets you look around without signing up, so it's easy to see how a thread actually reads before committing to anything, and the private exploration chat means you can think out loud before anything becomes public. That split between a quiet workbench and a public record is unusual for a question-and-answer tool, and it's what lets the same space serve both a beginner working something out and a community trying to settle on the right statement.

There's no pricing posted on the site, and the app opens with guest access, so trying it doesn't require an account. It's clearly an early product, with the whole experience rendered in the browser and the marketing kept minimal, which means the access model could shift as it matures. For now it reads as an open, exploratory space for people who care about getting the mathematics right rather than just getting an answer fast. The absence of a paywall in view, paired with guest access, suggests the current priority is getting people into the workspace rather than charging them, though that could change as it grows.