CINXE.COM

<!DOCTYPE html><html lang="en-US"><head><title>Just a moment...</title><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=Edge"><meta name="robots" content="noindex,nofollow"><meta name="viewport" content="width=device-width,initial-scale=1"><style>*{box-sizing:border-box;margin:0;padding:0}html{line-height:1.15;-webkit-text-size-adjust:100%;color:#313131;font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,Noto Sans,sans-serif,Apple Color Emoji,Segoe UI Emoji,Segoe UI Symbol,Noto Color Emoji}body{display:flex;flex-direction:column;height:100vh;min-height:100vh}.main-content{margin:8rem auto;max-width:60rem;padding-left:1.5rem}@media (width <= 720px){.main-content{margin-top:4rem}}.h2{font-size:1.5rem;font-weight:500;line-height:2.25rem}@media (width <= 720px){.h2{font-size:1.25rem;line-height:1.5rem}}#challenge-error-text{background-image:url(data:image/svg+xml;base64,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);background-repeat:no-repeat;background-size:contain;padding-left:34px}@media (prefers-color-scheme:dark){body{background-color:#222;color:#d9d9d9}}</style><meta http-equiv="refresh" content="390"></head><body class="no-js"><div class="main-wrapper" role="main"><div class="main-content"><noscript><div class="h2"><span id="challenge-error-text">Enable JavaScript and cookies to continue</span></div></noscript></div></div><script>(function(){window._cf_chl_opt={cvId: '3',cZone: "zbmath.org",cType: 'managed',cRay: '92ea5f3d08e746c1',cH: 'nVoQMI3V5oTaeMo1XsXh9c5MZtp7yAqAX2iL0AKEYS8-1744373334-1.2.1.1-BUWjsP81CX.PugNzQVCJBxnZEDXH_2f9DTclzdFlZJ9IOwlxUJQ3yrhQXVOeRpSI',cUPMDTk: "\/?q=rf%3A6724291&__cf_chl_tk=RqSVcFcjcb.V9HpAfHhjISkPESqWrDORTt_WQvrY0IA-1744373334-1.0.1.1-vaVDOXInmXTjz_LCzgmuCNhE3BTvVH_w5jaCag29wb0",cFPWv: 'b',cITimeS: '1744373334',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/?q=rf%3A6724291&__cf_chl_f_tk=RqSVcFcjcb.V9HpAfHhjISkPESqWrDORTt_WQvrY0IA-1744373334-1.0.1.1-vaVDOXInmXTjz_LCzgmuCNhE3BTvVH_w5jaCag29wb0",md: "_g6SFbZfNLG2P08oX.baJbbtUb.ugcoZzkw5URex.x0-1744373334-1.2.1.1-E8EJ2qRKCfipymgWVbNPnVXScKLjmQtZv.JbrbqwiUIfnoFF0jWvweEq0NXB08D7VfOnULrdTMCCQ1TqRQSVQrLhZ47fWwskpMYsfKRwcegUZboNXOuvrJITaSzXpeOHpL4LEttMb38Ym81LAlhO_d3YXCSFsGKuYV7MunFBUVw6ONY3v7_5KuuP6gYV_WSnvK3ywJfxGMCzmu.2G1WsSePuNMHCOz5aw4joMkc6sh4xZZfnOcUj37fl8JCu6XH6MWFW_8f9425UKIAn1u.6cD12GdyzvjzIs2UiI4OelqdSk4fnc3EbHD_i2yY4PXRe0z2XgqwNtO0LC1ltRaWsMMPNjx3Xdd2H88l61aLG.Vut4ZWvMSvc0.XCDrsgz3WbbP0m_EKs9Srjy3Xg_ay6fuxHRlmKvBtwmvARnudIPkntGhYbkOzHz5pjWt2DpgIrjm0pnD3ZeZAMs3Ru_W23kSZDb7I0MG4Rut62v3eJOZLEj1i07ayY5qa2ABOCH0x8eF4l6UIva7rwFjcZ06nexke5HCGY5_yFLKAmP5Y4d1dQTcgD0wtccjEwt.f_LzgMWBGddguU0FzQkkijKq5Rmbv0beVw5mMMmNr2qqndlLBDzWT3Tq2CYRLnowtMZsO.hXUmWTlk8PKVUWcR7Lf7u5Ffn7yJ_E55vicHJx4kVK_A5DTArLOKYohFaey0sgB2naq2kr.3zdaEhDG4vAnzIYmWE7FKskCFDICUyuMzcG6mlsBoBDuLYuNUuK9cr4sfyCsCVuZKZJLTfzmFGjKHMgtrHasezgbwC9OwJSCIvk1GZDhRYvCoi09NoY2A5T0fe23mUoQRZ2k7k3rNPp3mMBiZXzB_lBXu7EGp78PCuCe6Zne1kvXlpsEW_bkPaOxRZy10bKccmWi3qj5l202WLviD3nOFF8lSPPQzar0eOUadsUp6LlJyw1DHmxYFKwJeeVCpIhgb0oZaLZDnk5GHY1fTQlsc1v_Is.5t2d_FT6IUzJ4Lmt.c_yqGuADINhITnBCf8aHYrIptrIk3EUiBb3zMtQ875V.nHMUD1BZ1eWxDvbewTyTuGnqP9rfkZiD63uDtX1krbzSf_nl5lxVbghwJeOilzYAc1gWuw8CC83dJZhulp.BzNIPK539cKANjvMFWhZ784PaR1f3zsm1F4NL37tA4lULLFTFrV6vHBr67R1rrhD_9XuuO26dmHF7O",mdrd: "HtSC6DnH7ye2QEsF7YQ.ddh.uUB_H13IGKfMUNUqqRM-1744373334-1.2.1.1-zvyn3IkFhc2sMc6keJvM2DDuAZQ0ey0tNBeW8wbEqEH8rf9vvcOLewPayBzzXSjm70s5aLA6fNZn7Nw3wgPGLU3bEEA8Hp3y0CX2xRuoPA9A7rrkewz5vU2iTdGLFIRsY_cRdBZ93J0DEX4wcZu9Yeq3Y.d_G2Lt8OzpL14KpUVzOHVfc5yx171jtCK45JiN8loSIaf1eChhNPmunWajqGjJGTxvwS4gynZXAGnYwXVuQVvL0KSqa7ILwL0USfPfz_hVCGLqHdhrb.xsFd2oaVD9XN8Aw7hh7AQl1etQtOzNJ.6Ohg1xmkg6xZBn1.TB8RBUvQPt0VWCMXiKwVwY8h5hx1ROVbRyHur25XDi8DC_5aOx6Lv07Hx9dGtWb60Rtm3._TxwQRSi1pSlQ4fBfkm4IsQdi.eQ3mxAS99RBHYweqf9KU2GA2IU.s6KqmAu8pF7QA9nepD4Q5p3MaFv4NxBF5f1lQyKPgyYoD0yoQwpxAXEInjKvhT5eFRCVgw.LEPPR2tt7BM.sTvccGM5Fb7vlMFpEuYNd4L_bZZFEvXd1kKPZkHnZIukblUyVvYVduJgA8_A0ag1I0G.aG8LERvgySE_lrb5pQPGK2xc6pnFTfwjted62sUve3ezrraHwGzM4WQmbdPNi9lDolt_IGtq8PuUFv2SiHI2y9sWXNCDex.YMFha0aYDjVCdD938xlBKkQ8AEOyWSWnvEIso.lHCMCMO58GwHiXXUeFjzpx4nLe84qNNx0eEUzzBVCG7uTpUUZ3FicVFqeruU9byVCMM_KTUACT04UwOfqobYNZGBdVqA59k1nwzqiU4_hUycmQNbhBnJ_PMNRC4e5qRV.yNVdqrrQ_FIa3tckKvFOsNGphqhET.X7Avl4N0ReWrUtXJ3byotoVLUt2Csm8cRifHH06lsvaKPu_imjJVCD5NHv3rF.ndzAms_Sv6NK4WyI1DVc6wWaAJR.VJ8IhmImNOPTFHHewxNKxu47keVGsVbqT09OAiV5lauk_kY5VdjIB2oG8p9Xoml2wFX6hot2cw3iouy7IaQ5S4Bv_9nHp.69DGCoMUG_yG1GfsUbYNwFHG9bNXIbMbqWpWu.tkhATqO3e.6enH6cxBumV9_.se5exS8IJrNYynqQs7zkuRJrFWNwmYjqe5Zx7CMJ0gh1th7TZB1prAhbOZ2.EYFL0M2OgGuZKBNEGrClnufoH6nHe2KvXDe56aZzPdKKv9QlYOjqjuKJLB774YD1OzIdBXN.jjrar4NpFgAx4JUSVnwEyZADKWOjj5PgITweTDlGzuzNZ1NIdyc38iECBvkXhOBHXH.LiaMb64jvBEPqSdTtuDONLBlLKKiPJA9BIIHoKVSyb7.GAL69S0hxvhVL_vTtARbc.jeo3dP4Yw2cuTcsyS.hxBLBi8qG8XM_hhtinh9jZ2XXufW.3jBXIYgU.MnqDmhqQ2Gw9yays.rutGTkPOIDFGBLkcy7zuytBlXaNwAD8OCVE6QaAQ88kyOJXLpWbvm1jvp0E8JbsdVGWHK4KG8h5vMS3zZhVUEM9zrFgPOGZSaGHStq.AmkcpA_z3OBYFj1J2yltyrN9_53x6ECZPHXYYGOs7sOjM7SF_YhEEchhY5jvGhwoByFnF.IxTitTB8CC6TuMkksA5LEK.fFoUbOdlgYKXJM6F2gbp.o6m1RwZZ76zP6br_rlAyHJILABNEOmCgc1y4G8UZNXuQJXvJLHRxt1cglGMoeVYhdDuoGYp5OjiT6orjipzIST5H4gQn1mUw4aEYup4GO258I92._kTKa_2o4rLATIwtMAaCLwc988G_Ggb0ayiRNYJjHrn.MGqI0CJh11P.VkR7V9npl7eIeexoPQ3BoHQhWuA6mlpxB_fTat0wEmUtpNSSMa6MDAOz.0ZC42vFsLrKcgHJv2L0oCDiLNLHlrq6QonGiyKpFxffsR65YzoQCd11A01twM3U15fgkVB44SgNFwzAWD71FN1f5i3mewVBuDUZMQ43958smYqAYXPpLrpfgDx5jdNEE.mJJ5ENn2_"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92ea5f3d08e746c1';window._cf_chl_opt.cOgUHash = location.hash === '' && location.href.indexOf('#') !== -1 ? '#' : location.hash;window._cf_chl_opt.cOgUQuery = location.search === '' && location.href.slice(0, location.href.length - window._cf_chl_opt.cOgUHash.length).indexOf('?') !== -1 ? '?' : location.search;if (window.history && window.history.replaceState) {var ogU = location.pathname + window._cf_chl_opt.cOgUQuery + window._cf_chl_opt.cOgUHash;history.replaceState(null, null, "\/?q=rf%3A6724291&__cf_chl_rt_tk=RqSVcFcjcb.V9HpAfHhjISkPESqWrDORTt_WQvrY0IA-1744373334-1.0.1.1-vaVDOXInmXTjz_LCzgmuCNhE3BTvVH_w5jaCag29wb0" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>