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: '92d681092dbd5c30',cH: 'rH3zFKloL6sk7G61EWwVYUmN8wBpUhvOy2edOxmcGFo-1744165003-1.2.1.1-P0iMQ0G51OxsVXLeZQsCF1fcXdYjdextONJWMRQ07vf28oHWwz086W937bCKqroK',cUPMDTk: "\/1206.93036?__cf_chl_tk=fEBaBJfTJ40di33B2ZHOI1lFavlWGMa3yfRP0oVrw.Q-1744165003-1.0.1.1-7ZWNRFYxfRd1kHVJVLlLQk6fW8opDWz57I470OnoQ2Q",cFPWv: 'g',cITimeS: '1744165003',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/1206.93036?__cf_chl_f_tk=fEBaBJfTJ40di33B2ZHOI1lFavlWGMa3yfRP0oVrw.Q-1744165003-1.0.1.1-7ZWNRFYxfRd1kHVJVLlLQk6fW8opDWz57I470OnoQ2Q",md: "xwRkqaep4w1pZxO14zHzybSoGMJ3ElRpWBgzAVgSZGQ-1744165003-1.2.1.1-ZlHpVZqn_4d1rfbHgy6nRLy0F5N2Gg4qG9mHn6LX164SmoV9Azah982Iz_ZXcj4gihvGrEmOM1WB.byVA.RRdJHSA4XAMPjoODiSQlK0HeXQZClZ9ZLdmbXFJbvxtVeuCQ2jyWIK.4GStmtosm._B4TfZvtTFTakmQ2xylGGmwzIwZSXlsUawGM74YEqXhyMLNJX9pyGTZWbNSE4d71X_PKAxI8_kxZYfzP14McDTTbh_w5JbabNSpbxFIlu9i_imasreL0R1x8BexjRd2wK938IINGjTv4.eo6j99WDAbjQIDw1xl1yOiFde1eBcjQd1pltdhBVlD0dvwQafj7ATjXYXI99AC1npgCLgEMjQXOOIP58FtDrBU05B9Qxp6YhL7ns7Wn0UD.YNCQ2wRLGGPTkeYMg_Kk1VXrJVDgAgigo2D2Vo0k05Mt3voGG9g40clyTs1gLxM65.cXxRHCHp98cQb4Zd1k8xj2D8QMP6i.cDIAm70AnmPS12ySXRgl_TiJ.DcrwObi1F0nD5h2ZHFTSWkCRkMQqJscWUXkipysSrwUVaGM7u0ltjUXwmewHwS6Vzn1LaCqzCGxbp9pQDbnuwNLc8_E2HK7GrTRSzg0UJsLzlv4pqnYTGgdwvfLMXDL_S2Glecru3gXDVlDeuDL6qwRiHLi.6KifsRWDGXFDNdxtnHP7fIzIO5zVVNNK4MiP3LFq4UaltJ5kfc2ifPZv61YQMphCGjAwpjSprppf5AY_GBQjlYAia_UnhQpv0LKW785mjk0cSpacOPHSSnPNukhkn9aepODpdkUZrAwFCw4NsCttJah2q6gaopinXdMx7Ucl_tEVBsSQ2CyLSipS0rW_LazqyCTxllLzWHiNYszaUPHapU1g5cXeFKe4MQqcD1.sfuoOm1xVY2C_6QkeDOoI9h3RbAzbAhxS1uAdSjePJv8jWVBfUbyEgfGzHCdfR_VpE0YWWxpq3hMxre5emKBbbo4UjMY95Yjw7cnYAYsK8OeIwlc8BqQVI2nHm39u9SCa.8AtqnQpZsAAZSjnMIDEiqidKJzKEAGiDwrXabO1txP0WIpvU2xa7hgUFk6BbE75inC9f6wJpYk7hWdDYOstb6cyIMRm5nL0yEYtdQ4W_v21yHmwMuBKwKyGs_GVrOj1eFVfXm8Jfm53LWlFwJqPLkLhtKcJxRBLzpRygjJHsp4fd0I3MJTHFBUl",mdrd: "PQOtef49jJHuhwhOSVHEj5tRv2Qoq5OlvisBU30twX0-1744165003-1.2.1.1-100lYSk.2QyeUUyNISjCGy28lqVNyGt2X47jrxvbcJAWgquQMFqzP3IgdsnjKV209sztlnhd.mNAFGcmUxCnRkN9wKitEFRim9_BJee2W2iEYcibCLf4feY1MspaEW1GyXV3BluWJtIfdd4fewOkQW41XBZhRqkacqYf.bPff0w8bpy3RVNgyYFecXaExqg5Xf_V5b2PACwjUNRYUT1lX.xbrQz9ajKF1m6ccbXXvAYsqBt6mx5tpqx0kJf1FyBouLEzrp.vJ4agmTc.Tb3VmVvk4Dx0BEq2kzTxhNKZ04GZww6fkWNiqXV2cMTr5GU6RMoW6Ccpn.w3Qy7YP_1EJOq0tWvr4UnQ5MKzQT48pDqOLZSBQ4DyfBPxhZxqnUY_qXZjGMrdcNoFnpTiYSLO3NpcSUx.e7ITBcD7cw7uEzb5EVQukE4DNEsvz0r9zyNslEaDG1VqCy_50jMe2nAQLxoNB9lDB68rtcVQ_GvvRBRhy4JuWet5Rc8MXMLdPMzQ0JGZAyj.E42PLFnp4RdVUWrMCHI0drbMaeGUxzdSyI.n2VxqO0DwWqeXu2UdpPDfAUQRl4qQioPfWzs8iTq04aXIi1D4davzayTsvoKtR9XSTGqgjmu3gwYDBRCWB5WGjeaV__pAFW1O8cGsJILK7PfG0RgskoWJW5Qr5tuWXpRsTLykQFGZYGjWqoif_W66JPyQr5F.5IKn19tiqo64.HcXp.E6zH3yZ6rtSCVXSYtCa58fxbmV3CmuBSjnQU5_RGA0eo3bB0z1wRe2lnbIZDPnGhIEwXfHU5nAZDqcTLccTqhsgnNd0Gpe2j60aQoMTZy.qids4ObaHJ5WhxkrXlibsUknNN2dM_EGToZFNmSW.hmgHzffRNW1wKLlI.iomiagcOSu27SDZ3g_Vp6NRmwIlJBnLrbaA3.bnWshqrsEAVLzGL_ymcDHxN1BAdhVNS7qNOVqzKxH_W3EDjCB5fX8C8Ucdh5oTHhe.5MIVCQjlwaNvLPcg_ATCtYRuM4S35f9BGW0kDDkARgGQ8SbxCKLp2bedTqKmRoQWN8DylAJChNDPmv_Yf1Wg9ttopd6udPkdIPMbjUhx0rIOfUuOeu9QJjt8YRFP93Cfg.Qp4jeXmH4mRLc.373.kpIttqPXh0..64IPvGCo2G3NydBqT_Eqh4C6U7HXlh5.kRzTCQKLjApdUXgDNDOXVqHJ8B.rDLInNbqC4wl0CQ9Pw5PknPf7fFiV2M548mbv0SkX0_Q5KVE1H2OWEE6yfNyT4hCK7NIPPKWWi3vh3JQZOMtBIcVQg71xyPTa3RpSqwn3qHhnTSGtE_Sf5BWefnVi9ZFhET6GjYWrO_uiuhDTVQNasw0ESs5YIRuz.4qxAGG6eWTN7AMqOMvqG8dqaY4.jVx.RDvOgSUKzLUHM1rqhJxkFJm7lpsoT3JhdI0awjxxBsRYQJMgRACnGgwirfjuuPYikHrBAXKLJPTpMC2F3DQo4.Vp..3AG6d9bYhLVu_jUqDC_6bgFnmtIdSTsI146DsJLmclANznCrf31WWUHLCGdt9wPn3wk.X5suCajd2UDSZND_pg5joOCNAgyFdGMymKImtbJm.wO_U0obvXzbbtIwFe2FBLxxD8xQc6JtuPfQFENGL1Tq9If9Bjst2YaCzYnWyqk4_Q.HNsb2Nhs_noiU6ux84LYNTJsQFCy52WRJjAQKAMbscx5GT79kJDyU5RqOFRoZiazNgVmZG0JtsK8ZgBoSmltPudaJGcDqAD_uAF4K.P.0ufDnHBAEIyOHY5bVO57vJM.tA2qSe8IghOyyqKp_kQnzo16LL01c9AWC86DLnp84FB5bqReqnNMyj_YzQzlMfsFvgZqcqOz5wdwyDL.87X6JLRY9YEgXGUmDn_hRxB8NIB81a4gQwvakZiB2TpM4Isb..NoVT3byvtRDjwmxhlgUA3PX72euk1dLoqZesemHnNO.x2pVwnOKW3m7gcOxN9xjE3.oGnL6vqLXE2PpuPZWA_EGUUu8FO5aqV7Prp8Pfa5gfdcqkjT8x"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/g/orchestrate/chl_page/v1?ray=92d681092dbd5c30';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, "\/1206.93036?__cf_chl_rt_tk=fEBaBJfTJ40di33B2ZHOI1lFavlWGMa3yfRP0oVrw.Q-1744165003-1.0.1.1-7ZWNRFYxfRd1kHVJVLlLQk6fW8opDWz57I470OnoQ2Q" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>