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: '92dc062a6fde40d8',cH: 'a2LD3S9vBP8r85edxQQNr8gUL5kJmLIBUBBxFRZvgek-1744222885-1.2.1.1-AjS_Hv6efkyySgFz_AbTNQZdOQAHcxhMVmHt4igzavZmFILx5Tlqtny5UTvyPwdq',cUPMDTk: "\/?q=rf%3A7559586&__cf_chl_tk=8IS8bkI2R8RuuolgFAMNocQy72AQtOiXeFbM4QCpg.A-1744222885-1.0.1.1-zdypq0H2KIUDeQQI7Bz.cU8qgC5bTZLINw6ZNJq1yp4",cFPWv: 'g',cITimeS: '1744222885',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/?q=rf%3A7559586&__cf_chl_f_tk=8IS8bkI2R8RuuolgFAMNocQy72AQtOiXeFbM4QCpg.A-1744222885-1.0.1.1-zdypq0H2KIUDeQQI7Bz.cU8qgC5bTZLINw6ZNJq1yp4",md: ".zM_SrSFCRIWYNXFMgMuYyvyqq8H0_CF9gMoY1W17bc-1744222885-1.2.1.1-Ur6uHkCwdpfprQfmUUvccqJhYCevWh4YgBlBnyyBsrGIOqBilor3iMi9XMWLBXZC5EQzrEFKM.1JhD4gfXkgZ0gQgp5.G_7qK9m3W6bKTPT0JN8WRIGE9jO50l3G5pTf1o5LkE7tgFRCnDApNxKSfvAGgOlOTh.X59gWstNVa0fjw1fAKD2HOMcgWdgdg1dlOC1vaOy8v4WS7HPbdm84y9mhLYTdGeQkRzfrWxHB.EH3.eltncLIgJWft2a5JAu5deQTbjkuXDRbjystC7mGrKg0uJZGn1spQY0eil7ZArSHaVNNHUlBI8rbelzOJckzx92WAFHDsD1XxdOXyl2qcm.fD.apV7IkNK4YWmLiVFEV15OS14V0qxHZEDlRvvY4_yo5vXNHQapGoLgJKSVVztQNfFhnU9b.YVsHL26qEsa6nurk2i8QY5aHee2iVIMm9Xrlrcp45r_gEoKLDmL6r0DFzAA6EiRG2Zgyq.XcGnhEExj7CCRqWSXyNCLsJLecfrdHzPUVyCSshczDvyas5O4hUeFTY9aZYqYpipV9lhbXaUnX3VQoMn78j8iaLw77fYS8oDeedOPkQaqbG1TyU5QtEpysmhEO_Ib1NyDqLOcJevZNBpHxhirGaFa8D9GCYvFVklsi1IDzAUH5BanrMXUomypfTbaK_uLNBi9HQhICLOrhHer9UZlGflDRp4rNNOLhyPIcy.bNND9EpSxMaQd6aXh0GMfhKxzFhdc_WhMWY.PbT3Y26uSGUDfaCi_8SQA4w.Nc7lYCMV9TC9Hwi3Hv9HjK8H2indvLjSRMd6T9gpZMwiw0nhw4J.0qmrOcvKGeXJPwbXyiT9LVMyNcY4L.vd3pttfzKHPU7Xkbtd2FLp226MYr9r0dAz.yvL0ox6NJ3VLdm.0W1a430scmKcu_ztJwiCfWe3n6WHpoaRGUDjF5OntQsXdK_ZummCJ5MW2enJcqzbNkwndUHfDmC047YnIQ406PuQjrMC2GuWcjilRy6IsdyK8bbUnoTJE9.vN1dwpKgSSvts.cQqONPhbLuQl..udeQYjpB.zlGVDqlq3EGtxgN9zAn1wphPQGz_YBH.b8N9k7YFAc34jlNQWsxWszYuwM6p8OhxazySn_bzR6WBRuEQOhqcTaALMqneKkGD6Kx3bDYyemmrMOHTwLB9G1FGWNG4tpIyQ9ZJ0RUQ.WibfEoWmQWXwTAbvH",mdrd: "zD3q4CyHPebf0lg8tTL8RCuMG1I2cG88QIHwoVHJFGE-1744222885-1.2.1.1-hsUyaqYPyoTNUBRoCjXyKX1ioC5wqpOBPs6L_H8vgKjS1ddE9W.GewyYgoYOGQGtxmjvgjWN_0CIP_wKlewxqUGJYpMSnMW2C1DIRGr5JU9UbkTAnAVOmRJn_EBFNFFLBkogGffkuxp5Zc.lsCtATeEp1sTeLPmkIeu3cWdBLIsnJsZyAcBcex07xa.ji_o2JFoKVNB2ON7St46.3FIdCXDxOC1fn_CxQf7KxwPt6B5xVpFhP0Gi36pafmpZb4t4MaLcAG_70A_Y6mkfhj_FSkIR_ZPalRWBQttq_02m52TSy.WQF31Sa.TfZ2RoDJsMVoE2BFQwljjaVY4PcOxf6AGE0m225_bc2ZasgNrXMP3KvtcLhUmjNYJjT5QtDGI1YKkCdUJFJvj9l4o.1CdbBJO1XbFkbt0OdUOeNZxVNnErwBj5unZVtBCkFeb.Jd7BvatbWRWlZ9umBITF4wzw2oohdpT2zBHudpVjrOG4ZEzhI.k9X5e4Pv21fJAtMjfnId9KM0YtKKF5c8yOxs_BA4FmYoiOIRWV07DZ8t4I8mhBoUykkUf.ekOXMoFjmCUYd9tI044fVkuG4TGhnCGjBgG9qured1ycf7AKN9UtWPtmHEGeXOskGl_98AHGDRwlDHxJ_2IAdZ2FFInAup95avEqSiGfi_Y1dRdZ2fomWkpABH2PukDn.e.C.anhfAMk.AduCdgnhMQ7sxoNDbqlOQlGEtyIKSS72i.AOnX5uXSeanaDrA_2aj2FJti7U6pmRTOxJjUZa6MkH0MrW4e9cb30EEnx_DvqCcui5gXkSS7qimGjyAZsvmRc0_Y5z8OJoguSJD0elFARxYZH_jZ4OJ5JDOVOXf.98xOU5dXMVQ39WeCTyAIFvDPfdtiUjCDS4oDuUglLMHfAk6XoAWgbOuNuhv7nIcgWU1yWw6.bJ4SABU1sT_9imwKrFRshhtKHsJ5YtIkfg_QeEBO7OpN6kS7UZXqsE_mB875u2WkYofsGp_elZ.EfrqsGsnpBcUkpZ0VAVrOrBGtPWEtot4xTZNolgE7tjHEKypuGukTnm1k8c02YaV5G.XcHLhS0l4VS7Bvj3urTjf6VfYcqZqGF1XXEycv_3jhQmKYf2AX5b2s7zAZjQ9QI.sOsG_0OJgpOuswFGzdL.GizUTAn.91LaqqQN5in.yzhsH6NaYzY0v2SusfSjaIdjaBCjsRsS5e3Y7dIavW0xIGRRMjs3bBdIQZYJaL1dMdLBJRnI9kq.SYatZA1QgjS32KwdP6IsSZ6YUoTSLGznaX4ip3w1lM54dCwc2NfirSP5m9xH8a7_WKChueT5yiLDm.C1S3wPynOzHPfXKDcVr5TBdjeMmppyYUOO91mVIbihB0gy7_mvrCUA0OaAp9GipLOoWdMMqZ3YFagN0ggoUHjjuxPTcaaO930JpzJhs5YHzdQb0X9kMH5dVCn6zWw7m1Ir8.iM_XUpfP1kQzXQHbDTnq0ytoxPG_gdezlieYHTr4irwPo1xyvO5ywgq5YYYJCIZV9O8C2u3UY2Rx3ZeYrY9DY4rYbvRv_J.EBXarm5TKVvkGdkclRDaBu_U_3N21e458A2dvLY2deLL.wRcFSvw3kw2zY1GQWsJeBa16iY1fj3nFoLKpZSAWw0mVz3ENTJad_e5DnaZ_GO.kMLq6Fjd4xUF5HBKvJZuj3AnSoecZCSibfaXJCxapkdLeiEp3c3fpTLNFkkNX896Z6qm4Pw9vkKNaNBy8Iqs7rm19.LbJ6hhi6DO79964e_UHBVi9TklhdNOxwb7g9v8aVVwDaa2I4eRmW5FnrJ0bcHrKHjN5k0VqzYuNPnAVgW62lFpi1HJV4Kg9oFKvEp.NhZc3qlYipwjApvGlN6KWflvlSalaCKB9BmN31_bAVqYfmTU.qLgaRQM17QKcURpnGo_NYUHxpw0t0ogS_PNKDxyFYuX8MmI2ObxGIrK2QF8UPjjpTEeAv1yt0sXB53mZSOPfXkHH5M8mxEtO.xP6iQhS7CHYkI0CLZ2YIHQXrtwf7WlDzNMTtHvm5"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/g/orchestrate/chl_page/v1?ray=92dc062a6fde40d8';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%3A7559586&__cf_chl_rt_tk=8IS8bkI2R8RuuolgFAMNocQy72AQtOiXeFbM4QCpg.A-1744222885-1.0.1.1-zdypq0H2KIUDeQQI7Bz.cU8qgC5bTZLINw6ZNJq1yp4" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>