Check your own claim
Type a math fact. The computer works it out and tells you if it is right. If it can't check it, it says so.Type a claim. If a machine can check it, you get the answer and a receipt anyone can re-check. If it can't, it says "not checked", which never means false.Deterministic, bounded checks only: an exact match against the facts library (labels as stored, math part checked by Lean at add time), or exact BigInt arithmetic (60-digit numbers, powers up to 512, 4000-digit answers). No code you send is run. Anything else is NOT CHECKED. Each answer carries a SHA-256 receipt.
We keep the answer, not you: no name, no address.What we keep: only checks a machine finished (the claim as checked, its label and receipt). Never your address or anything else about you. Things it could not check are not kept.Logged: append-only rows {t, kind, claim (library wording or normalized arithmetic form), label, check, run_id, output_sha256, credit, sha256}. No IP, no user agent, no free text. A daily-salted device hash with a 2 day TTL caps logged checks at 20 per device a day; it is not in the log.
For AI tools
Computer helpers can ask us too, at one web address.AI assistants can use the same library through our read-only MCP server at https://humanitieshelpinghands.com/mcp (three tools: look up a fact, check a claim, search past P vs NP attempts). Nothing sent there is stored.MCP over Streamable HTTP, stateless JSON, POST https://humanitieshelpinghands.com/mcp, protocol 2025-11-25 or 2025-06-18, tools lookup_fact, check_claim, search_attempts, all readOnlyHint. Card: /.well-known/mcp/server-card.json. Rate limit 60 a minute per address.