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: '92d5b6b76bf2493f',cH: 'fU8eq4Yh_6g8zziV0cXF4.PAN4sMfJCxNHA8jIW.fHo-1744156716-1.2.1.1-VElBEDwMJjbTUjXjRkZdtAqxRDQxEHq8Xc9JSawNa9eWvxcTKDxA6qtHvYXOmUIa',cUPMDTk: "\/1060.05009?__cf_chl_tk=Eso889wK2EciHoVIeZGfaQ_ioFmLNcP7TV.A8V0rbS4-1744156716-1.0.1.1-9EUsIxVNQTW_4R.nqm8FpkT7k79BjmTCh8GkkOSELUE",cFPWv: 'g',cITimeS: '1744156716',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/1060.05009?__cf_chl_f_tk=Eso889wK2EciHoVIeZGfaQ_ioFmLNcP7TV.A8V0rbS4-1744156716-1.0.1.1-9EUsIxVNQTW_4R.nqm8FpkT7k79BjmTCh8GkkOSELUE",md: "8e85Lmd1cOrMgBqOMu6QO.2AEil18NyNa5wBCh7c0LI-1744156716-1.2.1.1-L1rSyNAbsKCwk8SFLPdrvu.PikiI54rApwWdOSKy_QuMNQdeLIFhQtBUDaqeVgNel3xctnpyq4ts.QBb0P7ZFusnU8O5XZi_egTGZ1UI7yc9_ftZIFJWpuWDX7iOyXmd7BXupctUIhD_rkUxJpuOuZ89K7j_H4OmcgxLdy9WIXqZxYJnqVd1FMks2hv5pxUYBPpZaUT3Y7tbBGHHYms.rsWkirQTmt3ZRRxiO9RXI0Qpf0xRFZWIHAtyldO6ZfpD9PIGWUkmnGQP9mYpf17_2ho57CM5_G5etzOvRzWePVVu0C3l_Q9hUGFOUcWpDINpb8xfeTvpoLVbT1KPlXMtaEptoJVuhokJ69ssZAH_Zl4neRFLu1PQ.EovPQ99iuHCcACTcnxz.8ZsXZqrOL2372Edmv8yk8J1_.eqBxZguBerfw7Kkp3zzrUJcbE8VSyLH1E5UIRui.R1zJUV.FPrgECmRyeAG4IYLuhsBnTOcFoXLyF5DkJ8nuu6Aimc7CYHUA0d9R0yf.kxnL0rS9cPINLeKG2GxQWfOl9sYEyDf84ZxO9kQ0hi.U41VjyhtJDYaa_Zsl6mt8O9Fvlk4F34dwaDo.B52ICWxRuVdjKUk1B9sNHRUoh6wp10h7OS.2bIcWiTWiS3E8UT.oqLdN3KkDcYBU0msk8O2ax34zpDKYlHwUQuTGXrkki9P43Ic9RlRn5fymWW0fcOwi0Y51qvf_ibjkZH_RA4e2j0hiFzxtQCYshANlrm0XQBuH8MwyuoioflpEBio_HpZbJjX5rOWlTmTliTUMac99rR_ICvHBtZL.0.UrkzYjywT_5srb6jui1iwdDYW71A.vRQKeCxhuUW0alyjYIP1_TakE0oW8w0Wi28ZGN54IafbHcde86lo2MtadT0Pm32toNfoZcCpG5GJeAGXeyZsY063y6JiOI2bwz5S8Ffec.GgDFSHvlBPFY.W.68OdLi0YnEhTvZIRlw6zxKJqLavjywhNueQqCtWCFqfd4CUKBmhJ5t.VdneFDLzJpPSuhhGXCiU5HOyVR9e5aizQ5_zmo2g8eva_KC9qqHEArgHX4lQvpt6FRoBXHBQ941S507bafWTT38CyUabkIkvjGJQnSv.n7jJ.vX7NWFXpPF_kfwa4KwvL.8Xi5.QsoPOG0AzrT.k4G4XrjxYx3SF7spFKrTBwN.YQkHtr211iZssl8Ch.VzEY_9",mdrd: "hQCx9whhV0u5ns2sQSC5.qcJx2Dhx_d81zQAW8QCcsY-1744156716-1.2.1.1-Laa.0YIi6Zlup7zww.f2f0ou9GadWi3C84hRB7QyPj7TGq9oGvXfKuNyCI06CDYmM7DaLDuq.8057jnZOlHvxLT_iv3qhp_p3yfZ8kUtJ6z_1Zn4rP_X8xRrK_AXbzyHI_Sr_CvgHcRUbTWU.M7S9gDk4Gndl7wfZ.vKSwX0P5g0rC7glEmXAxZlz6LzbllBORhHe3.tELkR10e.NM.Ijb5QCyPRYG8NwU6F4uUfG2CU5F22h3e9JcQWZvLntVVi8HqHMh_srdtM60eDNL_C53toGSiJiXzkhJjlz3yCyMiLwUsOuW44Innh9yjxij_y8paiIgOeldkqLmF.__WX.OPDemq71873EB7a8ZGUBkTwx93VA.V33_QCBWiA9zHefTDhKQLPEB.R5eZ0.yLEY20_IzKKAfVQ6RdBnAB30n75y65QsG8F6tAt8ObY1Ut0MKfAqs9c3ZWWKnGBmGhykRfKobxpwN19Y6MPwamP93HdLBCcek0bxK8c_hpyxR92pAQ1tBNg24_Zim0AMSMzOn2v8llyyuW9Mrs5YfzO_baOFnxjA68VbOxtIP6suKWC6QQIeyy1FRPSWmiuOoKCMdZyBckFcZO9OdhTLSq2HaFR1crFgei.gXBB7GtB3XaIP6euYkfMBnZ8GCPyCIpys1oQSUD35njnQ3d3wGoSwcylP8K_w0hcJMmB8WvgjdX2iW_nz7qMyrRNAE8mNIVTb0pZPbMpk6D2fRQKl9peFMptVDN3d1cnWbnBYTEwCxNO7AxLWDA.kiL3VtIyJvjMqK7iBO7pu_dNhJetnIQzs7MkFgi2ZR73GDX3uhWA3urhTs9LsJ2X8QL9HrEL3zrMLOyoYmB9DZWPhHyvpq_ZsTv7MLJvhS1n2A67qq64Kqs.pLsuANwflC5f.NXsQc.fabUx5C0aDYUgm9hEhjm0X050ng6xPq3XTyyM69QzyFE.FPozc22QNdiM9.81nB6KkWtx2o3mSHXrUxfPp5Vf.rWBgPFUBJj6ukV1d9l0Cy4ChFmnqtXX9PLhAGyDpFzkog604Sl2RalUBm2gHJxqRfBwmPNc88H7WaNPN20fa74OS37n5TAqcCLCiDyBvNw7B6Quct4XrLcHmD_pNWDIzXRrBAr71R57NqNzgfP1O7I5heb7G1uXS.z2eBBIzJHLfIwAMwwkSn2NhbQ21qUlEsHCegSPQjRzfQ6Ao3firzJlZ2P2kTImZgE84FUETEU68zUHWKj_ME49n5YYVDzPk8BqyakEt6sfgYMY3sIYWneGvzeEkrS.z.Bltb2KMv1vv5kyTqvtTTCEmU438IDJshhjClBa55wYMnObqKFkI69IOx4s4ufvd3dQB8SJU.LWka3n0btFnkMFkSty3tfhSn63GGahGJDy.O0DTzPSeF84.CHCD8EX94wAZGc_IXX99zFSHoiPf3ox949lwwJZ7VMrzosu8WyenkSoxRviVac9Rp5yy8EivFqbDeo4ZHcAk0kRbqdDqmclJ8UrDJTW3eT2VcpXXNUgMT0IuHjJ8bqF0XLQ4S.hq3PQXF77ntrQzLYmAc4XgearIC9kAkxAHPmE80ipTZ9g6nYPsy2ILdXSUer1vfY1XhcgAkzUKVYJXG2Ce.D9E0Omb2Fr3y2fcz6JIgU_YH1cyVcdQ94OvLJtQOY7M5A9Lxf4wfUhDB2dwtss3jKMUkAYtw_PITeG1p8HIVNjF.G4h1LZiHdvhwC4aLIENZc4Gcnqd5tqzPpPT1aW32KwxsJPtKnpPCXEa2lvGKdO_609SaMUTdQcH1Fst0U4gNq.3YVhweiTq6DnI3TeRKMQTfHBlySy4tcSfx74LpaeyKuzCBulDPilmDhwA7r6QI6qc555c_3hWPSY.IhkuMBskbNoMWUyne8NVAHQUdFRQI1gQfBxMIiik8ZFaGFUoQAnp4VyrysyXdTZ5RNC51rK1f4TL.YOMtXYlhZPdSu.smZIXZUC_KXGQ4W.T71nfDvWzHtHrt61xJfLhkzJQcavYYUJCZ4upu4ZJeBeRqXiXI10eSNZWl.Tzi5z"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/g/orchestrate/chl_page/v1?ray=92d5b6b76bf2493f';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, "\/1060.05009?__cf_chl_rt_tk=Eso889wK2EciHoVIeZGfaQ_ioFmLNcP7TV.A8V0rbS4-1744156716-1.0.1.1-9EUsIxVNQTW_4R.nqm8FpkT7k79BjmTCh8GkkOSELUE" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>