Follow updates https://wcook04.github.io/practical-formal-verification/updates.xml 2026-09-23T00:00:00+00:00 Erdős #257: a checked weighted theorem and an open question https://wcook04.github.io/practical-formal-verification/updates/erdos257-weighted-release-2026-09-23 2026-09-23T00:00:00+00:00 A Lean-checked finite-prime weighted condition proves irrationality for every infinite subset of a qualifying exponent set at every integer base. The paper constructs a set beyond reciprocal summability. The unrestricted #257 question remains open. The site links the short and long papers, a cross-problem synthesis, and routes for proof experiments and software changes. Tour introduction and example instructions revised https://wcook04.github.io/practical-formal-verification/updates/substrate-like-record-layer-2026-06-22 2026-06-22T00:00:00+00:00 The tour was revised to describe the project's source files and saved results, and to direct new readers to one example command and its result record. Microcosm became Plectis https://wcook04.github.io/practical-formal-verification/updates/rename-2026-06-21 2026-06-21T00:00:00+00:00 Plectis became the preferred public name, with Microcosm retained only as a historical and compatibility label. The acknowledgement is source-backed and does not imply endorsement or affiliation.