{ "id": "1803.01830", "version": "v1", "published": "2018-03-05T18:50:28.000Z", "updated": "2018-03-05T18:50:28.000Z", "title": "A $q$-microscope for supercongruences", "authors": [ "Victor J. W. Guo", "Wadim Zudilin" ], "comment": "19 pages", "categories": [ "math.NT", "math.CA", "math.CO", "math.QA" ], "abstract": "By examining asymptotic behavior of certain infinite basic ($q$-) hypergeometric sums at roots of unity (that is, at a \"$q$-microscopic\" level) we prove polynomial congruences for their truncations. The latter reduce to non-trivial (super)congruences for truncated ordinary hypergeometric sums, which have been observed numerically and proven rarely. A typical example includes derivation, from a $q$-analogue of Ramanujan's formula $$ \\sum_{n=0}^\\infty\\frac{\\binom{4n}{2n}{\\binom{2n}{n}}^2}{2^{8n}3^{2n}}\\,(8n+1) =\\frac{2\\sqrt{3}}{\\pi}, $$ of the two supercongruences $$ S(p-1)\\equiv p\\biggl(\\frac{-3}p\\biggr)\\pmod{p^3} \\quad\\text{and}\\quad S\\Bigl(\\frac{p-1}2\\Bigr) \\equiv p\\biggl(\\frac{-3}p\\biggr)\\pmod{p^3}, $$ valid for all primes $p>3$, where $S(N)$ denotes the truncation of the infinite sum at the $N$-th place and $(\\frac{-3}{\\cdot})$ stands for the quadratic character modulo $3$.", "revisions": [ { "version": "v1", "updated": "2018-03-05T18:50:28.000Z" } ], "analyses": { "subjects": [ "11B65", "11F33", "11Y60", "33C20", "33D15" ], "keywords": [ "supercongruences", "microscope", "quadratic character modulo", "truncated ordinary hypergeometric sums", "infinite basic" ], "note": { "typesetting": "TeX", "pages": 19, "language": "en", "license": "arXiv", "status": "editable" } } }