Paper Lens

Find original definitions and theorem statements in arXiv HTML, with source previews and links.

Paper Lens helps you find definitions and theorem statements while reading mathematical papers on arXiv HTML. Look up a symbol or phrase, preview relevant passages from the paper, and follow links to their original locations—all while keeping your reading place. Features: • Find candidate definitions for mathematical symbols and terms. • Preview original source passages, including supported mathematical notation. • Preview linked theorem statements within the current paper. • Jump directly to a definition’s location. • Save your preferred definition for a particular occurrence. • Request cited theorem statements from supported arXiv HTML papers by specifying the cited version and statement label. Getting started: Open an arXiv paper in HTML format. Hold Alt and click a mathematical symbol or reference—use Option on Mac. You can also select a phrase and choose “Look up selection.” Compatibility: Paper Lens currently supports arXiv HTML and supported ar5iv HTML pages. It does not work inside PDF viewers. Definition detection uses document structure and English-language wording, so results vary between papers. Suggested matches should be checked against the source. Privacy: Same-paper lookups are processed in your browser, and saved definition choices stay on your device. External papers are requested from arXiv only when you choose “Load statement.” No account is required.