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: '92e7eb209f82f881',cH: '5XOq.Afqm_DQ6Jv2Rmi9bUSU.BONm4EDR4AJ6zdNWN8-1744347607-1.2.1.1-oMJNK9CzJ15AtWpETga5tQYxdUyQXApTkbUfKdvKBwEihkxBkPXtB1VgsA55G8w2',cUPMDTk: "\/1114.37303?__cf_chl_tk=639aRf4zAKY.jTNJeBr7bBv48aJrUS_GAzbZzk618ww-1744347607-1.0.1.1-qrtZ4_mqz0R3tEgY7JSlNQkhLb4JeatFcqDU7dx7NJA",cFPWv: 'b',cITimeS: '1744347607',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/1114.37303?__cf_chl_f_tk=639aRf4zAKY.jTNJeBr7bBv48aJrUS_GAzbZzk618ww-1744347607-1.0.1.1-qrtZ4_mqz0R3tEgY7JSlNQkhLb4JeatFcqDU7dx7NJA",md: "TetcbLeEf9tHTVCpW3552iA2Hlz_MMoQZpUe5saQkdg-1744347607-1.2.1.1-GgoiklV4TOl3LQ8sd1bnqfawYs_AF4WMuYzfNyFEyWz6JxC9Y0m0rHa_Um0lSLjCXugYdXDVIBcHM5oCWonF8Dunt0fJqhQj6qTGlitSosf5YPDExZ7n3eyFh2n8JfE9haBYlqalq3IVS73ZJKN02pYX3Rsncc4UU9DaLwNIrWpDxXAKfwrCv9vgAGgwkfbBU76UtOKEuq31Yvd3_clPv3ffWUwUcKv0EbIJvSqOJcut8EhYpriA3AeaYUkLPYzgsMq1xcXcJL66AV2J2PUwgJ8KWyHXIXod3CGfcnG0nnBq4ludP9yewaIKdhwK651fdSZ_Q7cUwJkeAXcWPkuqFr7RdbbNfEQvZvCO4X8hdOvOM1nwW2PX06ZQjoSUh0q7lFwJQW9JMr4acTAKCOiP90fjBL0U.Fy7rCLpsfbFWkZrKFJcXMU5.fcPKgZ3tJb2krVsVWBVWapDywuV2dmtxKVSBOyUCXnICc9Aurbn85loJK8MA3tqPxmofliIRTvAPk6em7qYJtY6uOrdY.3DN.MDvww55N7sgIDSsfaqiViAeRDJ42HGNjpDDWr2QHepXETkBwWhPXihxu0oqvGTSyRg2UGDQtTm0Yu1uaN_9H2jcuR9BSuhgMbE8rWcB34AxlPx2VWsY73HoUcpQCbkNJlCJb5KQMJF.2x9fatAgTKJNDcr24TgedKopL3iS2fQSxlW8sWElIUDIkl4mt.BUcIOZIemT8De871rtxvnhgcNicS_Op3Xwz37m3xUAigVkXOdS9kWM1LXt1PoflSXgYXY6Gj.kMazEYrmix.SNJh2lOJCRlgPwG_Q6MHOjUQXjFdpr9Smjw6RFQv02fCPbABub1.11m2HdbqXooHSTJjeZRUCL7c6coM3ZV0ry.zxe8P73Wewig6bebA5PcjHv8_dzERFZyjAln4e0Etr5NwvvbaYtKK85JIjVfDw2maUILOZGpIIqQu.WcHRKM8wtkcGNYVqgGU2o6fe.i4x3D8bX_4QCFSjXvlF28VROkYgLW3NOg..N0Ns2U8hc5zBUFLzwDe9FQ1ZXXKFDsylIAs2Pho5rCsi20A.6QjutLRDoSOo3S0DIQHU.feN3tS6mBBaHlJmFhCIBuwSlzWVw65ETaLjPvYUwkOygBRQtmCKVY13AARfG5r4q6tAxui5lvtjvKoEGsTJ0OGwJ_16mAZjwnCugXX2xWfts8Lums3R",mdrd: "Gm68O4TNF4hDghNz_lTw2Wph9OrocEQKI1n0snHgqEU-1744347607-1.2.1.1-cHWOitcObCt.j7Mw2jlCBPuxzTKkibK6iWF6owonz1nX75SyVJ6jY5Opaun1hlZJVRHUA2.wXUYgX.vn3x.8IacLbtXPsdvF4wSEzLI5TiR6EIycyBlkHF2_WM8Wm6gQmZQm47h.jwtFpX7UTvUOn26I5MrPHaxo0vs5sG0PdKoB1aVSyVv7UUgdzyoP6YibREOVHcGo4yRmxuqbPSNGy8xl_s6GlK.cMaaAmPUtm1KkXjx1wkGqfFYo6LJqp_CrmnHNFODc3BxcGtP_jkmyeStNDOSpiqCbaG0cbqcczE.y7VKMh01cXCiWq6Sgcx7WnhdBoV77VCoBc.B8JRmFAkG75rLb2QKJW9cN2xjueipzzAf0UFEt2tnORQ5QJTW2EbQghYJ2g.N7TR09.yC3qhpgGdObzw8m.Dvy.UiuwkPaL39sMb3687wuGAJVwr477KyZqaMn4RKA9IMs1S0Vs5FgLuQlhWoCpIY6V1yGWh92wJaVoiUHQBv_hMSrjNiBdAdjS7oOf3KmDfzQyUwcQtZdbPm.vgKxvGWALFMR5IPSBYZscR0MXYJ7pzbRpAyc9zjwtgQCp0z4to5YYYJlNeE8GdLU_8jXlFIwpRL9L5_Xi0kmKluTlbdAJOPqdnKMUr5udhRPEJWZxrzeKFEJd8Jh1LMn8ttMjJM.oB9fXt_gtrdV_rI.IWQjB5Vf7B5bHgDWnDYnbEFTwHMn3u6TrXHLHByW5bIJBMfw0NcdF5A6hVqUy8veI5zeYm7R1KHiyzFiJxmeh3e7LojbT_PTuwzVUk5vZolSa7P1KCiZpUcHrNn5lCX5PGGaDARMJiHt.QDG8ZhR72_h5nOKlx58aPEce_IdZ9AYwxDu7CSzucYQlG0qOrsveEwtUKBlVXmv_1hB2DmgqknV00RHOKBqDbgsac6VBSZE3UjA4hi9H0DRHIQeiWc._Uj7TziCG99XchV0fRNTyZBKXFJIl6zQ9l6WumwOona5.6nKIvuxUHhT0vo9I_bToRWSTUinozNf5qFD4BM4dlRtb8myVa3NP770PtLLcglzTXxuAENE5dT4yLFaGpZnC9RbwFkNRpMk.SZtkrU_TmP6mgfIKWc0JUVdgikj44kNGz.3vWglfGDtV5PTiFrenOXz72EAWJi4scy_OxCNIA.psAZdjOaXW.bHQ3ID38PU28LS4NtinyFduholrDHZiVmaa6OPm3OVUaHIrLfb1j9GygXlYll2vkmpjzNREOLHDQ4M8BwFuulcB1_2fbRvwdS3lVRM2eXTaQS3kk020egdexnsz_EK6X9ublYzGaMR2khnCva8.0sZPYKQpnWrcJenuSzt0m_L6I8KqKvbCD_HipmVQyDLrPvwOOA5A6hqf2lL_4LdybWFC8Gn_lw84dQ9POygbEPx.jYrnSMkQ.X8OVTZFPGulym1_5J0CfOD6jPUyCZY7hNmYTvHxl.fiHK9fi7XEVPJhYkqIGWPsJ8_4DeMeB1r0fUADsGFMSelJS_AFLR5g36uWxi3YmDAKPq6ZO8OH.FJNWPnxgphIRxqZDgAuQj2YrtEBPZsVyeDJDxM104xmcRaAV9CU_Vhns6tTML50ApX65FdyA9ZPBSqbk9OVzrs1lhNnY5OWaxS7Wmqt6yYef3z6vuCFGdC78ebMlctCzia2UebuONtTULi7y5u5.JogDl2LjmyjsKvSqLZG4ZHLiQ78SYIdTK_joq4XEIu3LERyOeVdBt2YjDAtrKdZ25VteoKSN30vUbYAw8rz8elPJWjc6xPnhFoA1hjK811Rk5vM1AAwlfZEPSsehD8JjZ10lG0v4QuaO_r8Y83f02l6GMj5UkVTM5T.nSL.RHRCMJVx7X02xoYYTtKJFxOYhs3gr4cCcvXejgQxVurKQbLv77cwlD0YtrE_1FFMnYUhib84SdVlRYntwxJWWeb.E34g8Ooo9ocEzmLSk3KhBqpnzXILAljCGkPqkkDYY9qP68SkaPGva5HD58utzcziPbPGp20B2hMMVGcXYwhsyR4BCv5GRodKTsWUFgPjBK9pEyV"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92e7eb209f82f881';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, "\/1114.37303?__cf_chl_rt_tk=639aRf4zAKY.jTNJeBr7bBv48aJrUS_GAzbZzk618ww-1744347607-1.0.1.1-qrtZ4_mqz0R3tEgY7JSlNQkhLb4JeatFcqDU7dx7NJA" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>