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: '92dcf25a6ed25f70',cH: 'LEjncd2rFaFUcG9dnuBsKXsFyXwblT5Fh3tXs1PIh6o-1744232559-1.2.1.1-lxSzGr6QInOhZAU9G0bUYy2g9nXFD.x.KuB_3S8Dk7NnNd6Dq1oKxAim_KftAYde',cUPMDTk: "\/?q=rf%3A7363415&__cf_chl_tk=9A7qWWveAgRz4Zr5B3oriXq.y9tM7wXZmQuT9W9U6_E-1744232559-1.0.1.1-31kRc.kT9DiM4lHdJTGaq1aslsi5ppfmbOjokbDJaaQ",cFPWv: 'b',cITimeS: '1744232559',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/?q=rf%3A7363415&__cf_chl_f_tk=9A7qWWveAgRz4Zr5B3oriXq.y9tM7wXZmQuT9W9U6_E-1744232559-1.0.1.1-31kRc.kT9DiM4lHdJTGaq1aslsi5ppfmbOjokbDJaaQ",md: "R9FeAX7PFVrCtDUljk.FnXaYIqK4UE5ElvEhJsKuuZU-1744232559-1.2.1.1-U2OesC4h5SYXTPkOhovXubXRD6YYL.Qh_5thDPNkGH0C_WF8_K7zUVeUnb7p1prg.AsiD1cxrYoYDmfsUj4R44Upun6mESXWMFT5JMDIkYeCl_IWbx4uocc7tBcodnji3aBE5KG_mQQw.UDoCrgLbiAoZ5PJINBlv29vurND8.TzoDX4s6CD2WcgrEgK_2gk94iJYjQkz7OeqnpIrwKcN9nNu83L4vKVjZRDS.VksYFS9mubBAYoRqw45wx0ebbvE7_0ZMWolhfX6LgUYclaCqjQf.roY3S7bd2GlWFyVpZPUEmUYxYZWawRVEAtNGwW1kZ4PvVZacqi4GRz.LZuW5vdAGME5KRfUp9Wd5zICaBZ4Ohgg4ln.lR9vgGaUzdC9jHX62O8DOflrMF1.r9ieDZQ3Qix8vQpV8nmrfmywPoYWRIkvOHJAJqb6Gco6xMTT8YUraE3.83gN1tQ6qIarGjD3SJCvBMI.2LXCWiEm.fH7Ja3VkswKI.GH80ctcqK1kJfOWlqR7edn5_Nz7KAiy6bXRFgK1JZfZCOk1z8AzkfWT91yCb7dyfIY76H6HUDxvf1Q4s281aa_u.1Ud811EaqNK1Wn3X6h8FZDuqUdEvnrLixkGZBNs2pIgZ2OZPBHMUqwQpLP2c.oTzKUlQQ7Xlu1Ym66ZtDlFthYLtEyGYJm0701Si78O9WgfffbWfkzCSR.GEVZseDDc5Ss31ugavk1M3RYMszOVIvTxICHJpSYijnPa9McwuvLkrvZTlbry2e.vuxRg2frDet1kMrDwxuM020llBs8ARdB91_GT12scrFRfOCYZlfkeOiT7xbQIYCd5qCfiUvu3VSo0agbZWGni2aFq5ywTyKo5HStvp5gPN7ifR4VT7KD9VAtftga2LlxRac.9oK5kwpwPaszM2qOCf8yn9qrPyawin8r_zm9OF9os4niMjPPz_v7sB1IoFEZavrrC1iK2RgloXWgzvf8.xRjT9rI8AJv8LY5S1CuIW3dxWjihLphkE5cFCyxfysMZPlfbr8WAu.YRRFv6zOGWIf7Y95q8Ds6re91a35pZtpuUnFdgJiH9x5vyrNeRdVWnbGQNws6fLi3uCvlkmM6EkuliB7dY_xID_wv44J9h5acGtsDV29VsMKxkKv3BZzMdHHzVJ2PjRQzGi52lOIzn_kQqL2AGSv68gxpOiUYT_UTZQbSqzHdfu9ooQ_",mdrd: "CcrwmWaHD9XP18JCx12gKKV4Q6dxBjc1pcrcUnRD2lY-1744232559-1.2.1.1-7XebK5Mh25wwBinmEFpzQB67la1xh.bgrReXO0F55qwoc6JKSWAozv9k._hO5lgDqFO7O4r1tjAQaP8XJPanvOOUnd0ELmxz9f2sBlA1cP12k8DWwJpW5GgrhfOCrA2k4hBlc11BYJ8Pc2xLF5YU3rlu7jubGJnv8D4loylse5X6GRa2xZnncKIhFGYc0A7EPQh0YWmSzNknc0f5truCwTC8k4tSrhXhnXtCT0imlRHQxnhXIyChDfS53YTcTnlcKsBiQlerSBkulRIAO9_ohd1nFFO7iylJeHBbJ_Cq0UFyqqVMRev0nwfclzHdIDA2QbDSAUpcSTOMT1KzAIuXjL_LsKcljT.lvrMbaCFyWYWGuZ1OzY6meXR9NIK8VDCoBj96I7h53fH6cY1JZvHrUEZ1PENG1Jr_xLDzI1LzNz0MnsUmoa.vlo8.iX1UbxTUkL_0IcYFxJvW6QoDJE3lVT.p5FfkMBfRpAEfUj9Lnxg9b5_EndmT9zM1oOFVMQne_E5pdJhf5MNXFOXrN0D1kgWpQWXcBeQmmMarPIBKXHmr_safmI2YlSNlGD2IpvCHxTMpjLYpVdlWmYcjajangKTV_oUFU3BPQOiXHDrgzMh4pXdGsOpytQuPOrBoRCQ4LnuYPurUkvbwF7SqVf4e_7YkA8gRnt38_Q8H_UpXF40csvdPOBiT8KcOzfasSeB6SvqReNbjIyYZgjGSrCe4eWZ_QV9UEsXDiBGdOAgI8OY8OdeeA1sRylahKspHTyv_oMx.S7MJ4GQ4Esbx5MqFiuYvJLGAoLUkWnJUSs6l3lnNLvDDmbkH7wxTOFEe846zLEuFNjqJqtqKLJArEBR4bGVmlePtxL0myb.C0GPQ4hYF0JtJNyyuFlCOcyXFZUg5WA7l.P1BTKA6v1GgzxZFW1NzcAMpqJjvezieyL9LP1dYUZFmgILUsNSKEqQlc6NnhjLuke5fDFImazV_DuJmQ8aJLYnTMHQL8PIkVwDw3llSDdH0RgPFSFkyxGg0Z_33mzmEPe.JnsdTSqJtm_XREXiWFMueyLYEWr22ZYGBBJ_UIsWoSvD_L8j15IXSKkV4xh2Qg4zVWstMdBmjVeRulfsgRA_QODuspfmdSpVX0vnIrdPIHrD28dRhNtolVvtRRxKRBMwJ_XTrZCopntThQnl1CoEqITcFgyMgSG6h9bGS0BBPkKSS8diAkswp7IACFJAJsVlhHtTPGFR2VylCr5fIpW7WmfnITBu8xheSI_F5dx2i098HcFFhtVw1xyaCtQoiq4.i0PeK1H27uz6bWerccu3_J6QFD3bBxU9uZ.5Do7Um9qkjdO1V8WZA.XJlGnTdTdp0jfJ4w6dASkoEsZRWc47SaoVPvxo2zkW03z.4XYm36sUtU0C7bXEZDjZKZY_ctG7tOb6XfghDaQmpCxvh6bxx9A_UgioES8Cmzk2XVZZhsFVwmImhdiTTK1y4e_dLnlHomqMEMXL2wXNCRkcHrGNqFWCeX8JIkstqTBxHLLeHEXRuZqBW6dllfDLKE9dPn0SnQeniP3_rWCxs.nCeYUWv2nukNlc16Hn3mjRLMMCl2y3ZcK4dBTLg6579X2yw_qHBwWuv8Qf8tLviXdjX6FrfRqFBKaOOpy6QiH1LkHiYsdCS0DhSpDyN0zkRSqsnK3qq1j4cDV.E7WW.EizZFVcoiVeXfY7_oNaq3RKYSUVpTy7VzGk4TFGTdTmX9ONNnef3OtsP.niSYTvShB_GdEVbigb7VY2DXFSbNIk8zWhVBSwvdvLzGHAEzG3IsKh5d6janA9kGns_NG4pR0FmrFjkPKy9fI8cM6Fjssz6eh4DsfQDgFGEqAXm47vrlGl5xbcxXvqY4r3I4M4XwHeT.SAUlPchGsqw8rtJRe_vaBSEIBc7DgrdYenmcx1ecf7oyCwzgNslxgi9DM_hdVju98j5BkyHrjVKliQJrG_TkxowfOvhObsL177Yk2BAYItEqOIjbZ_j96MAsYmoh4SyjJG45LP3Pt69WezoWZU4jCY1SUtQSeI08.JJQGeH"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92dcf25a6ed25f70';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%3A7363415&__cf_chl_rt_tk=9A7qWWveAgRz4Zr5B3oriXq.y9tM7wXZmQuT9W9U6_E-1744232559-1.0.1.1-31kRc.kT9DiM4lHdJTGaq1aslsi5ppfmbOjokbDJaaQ" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>