CINXE.COM
Just a moment...
<!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: '92dfa3603faace65',cH: 'NCkBMRJdgO825JLT05Z2A7s3Z9KNpK4GW6esJKns_aA-1744260782-1.2.1.1-W09WXx6_VYyxfIPwycfYkubo33ulPO.9C2LVwsWSUNantbO8hQtvLrLWLF..Tyi4',cUPMDTk: "\/1153.81407?__cf_chl_tk=TV0jfYEhRik3JYQ68LjdehxMFdB4K_w.LIg7Gy6dLVc-1744260782-1.0.1.1-d2VhTri3DtedQ3b3ezPnxGc27JgfV84COuK.E4adqqI",cFPWv: 'b',cITimeS: '1744260782',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/1153.81407?__cf_chl_f_tk=TV0jfYEhRik3JYQ68LjdehxMFdB4K_w.LIg7Gy6dLVc-1744260782-1.0.1.1-d2VhTri3DtedQ3b3ezPnxGc27JgfV84COuK.E4adqqI",md: "eBNHfllV25j3zJr6itOXTVwsWdPeuPrOJLGjFS7kg_E-1744260782-1.2.1.1-5RdVfT_RALI.vzqI3rSg3EtYIqWBd5pTqRImPprqwDJozOsi_nMFb7YforlTPHib1vx4kYuh5n176PBZdSGDQyQMHAeZQTB8dtSrwjGczfJTZ1_JBjqDXYmC0hTnLurWnL1ery6CT_DKzamEWaZRG_pLqqm9BkHaGtlxUmX_fJShYbIaEgj2bM3ZVlJy5JJri1KdWT1O5oC1lQfLDv_dcA.u5UXpBXTQKrSplGjsDdqqlpPq1U62ouSwxQuytZWyHz1hMlEYrnd4w3CF8C29PStf_K68Yv.jymZFtmUKBfySqPolLJGsrMa2iL.djMtZ9rRM.zKdLAL2m6dUFieZE4UwZa0OjW3iSakPN2M6CUnQwty_Wpob2VuEr.STxqyuQPe9PrPRDN4HomDLFWybEVKq8OmBl93YN2yNiDuFztfzPagN.nBscGkS8DRymNRyDWUMz4aHI0_osSjSslOnN2nCCWmR5jAEUHSveuBYWOL2UWPXWCfGCWWsAB.dfEijkgHBVZQuwVLm.s.oAVVLMCbz.V_Q0WFlxWRo_IB9NsIY2Cqb1CeolfaWxaEL1Vio_LdP_X4woX2jHP.xKMkL_I6zxujvEzArO2eUAruQeg9A4ccc_DfxyxLFY1e5j2lN.5Bwc6d_a2e0NYTFifvJc132q3Kot_sr8qayR2Gkh3fM9FSPUGt1NaiyXqIIby4bxbQx6qWIMORgZx6zwNk.RLCXyNxIaH.7Qyl2ESiZ2K4HbS8sJP7TtO0NRweFndPh3dGstM3GJjpPP6FmUw6yucJk6ZAcok5m5xcaZ0chgWo6VK7mq8yTNCLWHIS4me_Jv2hxI99ylRP2citF6ps1O_pgTRDFGO_Arh6K7Rvx8cp5q..HeSXl8V60NXPTUFRz6OL5f43OCkgxWFtfWhDSXdVIRVXsrT.l4.7nsway5K8QS4GP9HMs1UmvYInDfnpMHwwvfrfpEUt8BndJUYyW19URCbFvIX4cld1.wYx63V0MpWEL1oo7xv4huzgasEDI0nb.3WAUbWLehl2rQtX23CA.3Zth4j5uDAINBBOvKHReq_NNyDORgvBa12MZWTXAw_WB.rwKej89IesJuwwJxWTTAKwPcrcLX9veR8QbmEyyuzeuBX_XdOOZSz5hY4pMxyNJqbXFbN4ASNmA.ilW7BSTIMiDTucoGH3SQuL.mGwJUoptjDJzZG5OUGHsmudc",mdrd: "DWTVKUkqsHsIqrPRnOYj2AD7tM3D4qMSapNKRMD2L18-1744260782-1.2.1.1-sZksrDCRil1KwE._SbyLbKki9HJ7eg8d8kg.oCOtmOU2Ha8OuWap49EbJjoVsilKmlOWhE9M_Ib90C8ZlAKc982LyHHlnXvJECKkgFD5UjatugJ9jlwXvM.PECrtncrJGR1ggQ8tOccY03eolfxzDpi9YjayDwNBeHLG9_tA3UAmBnyG20QuSXy88s_3QJIHKB74qD04N1EaSAL41m_PmYFO0fiMTkM0bzvAUtU81wMtlZapx1MeQSWg_KFdns53q199LUlHocDiTJNOWfyhBb6uzT1HC2vPMvr05AVbOacT5hBOp3foStkn26Ik.Wa3qRsw186RpClYxQ2G949y33.W8.ZCVNUsdXVlrpsTIbEjZAlisX7HGd89CNs4A8pjAiDb_w_KopybIzCjoGVyBiULBJDTxy9FCbOzGSbITiAH5vHJWTYNb4wlXBreDLoIUtsasRk9wkW9cZ9rvt7VHKSCPjLiddBkPZCn8s2D5hXxt8TEu.gN4RKvY9.RcsQpUxgLgSfkMX8ZxB1AGbRgepjnHZjllSZHYW9M4mEWpJ5hgNHANNv8Hz1APV915LaOuEfAN1SP96_AKRCf7LE7OdnZp4_RT6OnEIec_atTOP_0hEvJRXA8AzmNO53N1k.zdMv.ev9smtZIyqtkHzm9BFduyX0_cHHz.Eouw75fFcmjVUjZOzzHX7s7Ert6b3X95O9O3vzgQj0TZQoU4ggXT6aQWULvXPtSYx2ZqbJNuWsEIzrSmHofN3uwDa0qepuG4mhRfpazo905n9LXZCWS3OZuCc45hP.6_lj.7Aunb3gSS0hG8v7ShCSiUmnmy6fQSusfczVfdZELIvi7bdjUWWipyLh3CDGTBk5.UUA5K9WObhJbGiD9BvLQW2jOs.lAcZmkfJbsTZPcDo_kzLITBVvyLeg2_1GNmB3FpcAdKwFy6Nda_NtUwHr7TL7jj1G6bG512RsxIbQ9D7pnps7PZT2CEf04ZetrO_RW0vd3FHgdufauxkoQQ4HExesxDzW4rn0LMs7Qi_Ti9PKcxqUyjmj_1U_81Rpv6Dxvjon6zPvhtt6r.7t3hqUV_d.jhbAVDBhfBBAQKGRK7VUiz_w0wjCXoEGs2G4pIqM3zBqZyoreSDQNfNvk939AXAhHBa8MoHcVzgzF_zaDFGnGxFCnl6D.6sI5Nxp.sI4y0Akyw3ukAiLTw5G34vJz7l6zn38pRbhBx1GHNt4MDsq8RBVb_VRBcEjtheF.PHbAoYamEU8WUxmIuvCd3LO4_eBFa6DsEsDTe0jk6PJnHn1HpAF_qIWIaZuzqPAidppDg8bxAIYkrErryqFWTOFxD77xzGsIv8qm8ho_hlolnBHEaMn38M.9UsgC8Fb7HhO6W3T8lkZly7H_aqXRscQM911L7HFYIuunlrHg9g20SmNv9rPXQaguZqiRuIMOqAI8LHVh.iX3cohrAxbHltWkmdmZu8ITBy33rc.IWpQQUBQsVX7ksyjlR7kwc922BMmDmLy_b6lbrffR_7iST6UpXoG5KckYN3Yz7SBFWmvKMWITd_CA4_GIP5NuH.nU6Pk5HdRoD5cEsc5c36R1xnCxKByJU5ZtEqyouwYoijnz77Yj0k29wX3sw20n73EtmaYKvi5qtA3NblRyhALkgfLpzj8WpSPZiTcnCFVvgzFTKTW_E7M_gyiJxxWsutELC68IvDyxkOHSz3Wy.3ce_oqOPmvBJ3Uhxa8MhcTPhN8HKZNX8IEU0_8my2AbZLOhJoVCimOiNDdFf25QAB3vC6mjseNVzrtQYzEyO2XKbAVdoUhoH_AMxHitPkp6SFWCzPn0DGK1zs9sYrOmoW54.zm1kRHHxNnQssw0H57jLHDzy0iNPbJOz8_ODqncf.gtAMGdGTg2_wSnR5R_RWZbMRwFBPBnLc8v6Y1DeCF3hRs7n59zuLqTeGduBfpbamIsZM7_oShYKrPV3knevkGcVdwnNIRTfXSqYHxjptjZm15Bh3baK6poMHJB7K7j3T560zZIMTkFSSw5beVZEYJILQMh_wbSlOkyeUCnEmA4SXs8xKD1xsqLkQ"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92dfa3603faace65';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, "\/1153.81407?__cf_chl_rt_tk=TV0jfYEhRik3JYQ68LjdehxMFdB4K_w.LIg7Gy6dLVc-1744260782-1.0.1.1-d2VhTri3DtedQ3b3ezPnxGc27JgfV84COuK.E4adqqI" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>