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: '92d7c4435bb86027',cH: 'lpJVjnjxKidgzXCldIMfRV.TsTRbZiqHJYQHZsIgGlI-1744178243-1.2.1.1-IX_c79OAh_XLVOzXwUr.R6CKBvwQq_qn9O14amh.eqVTi4Zy92sfLhWPklsR5ufy',cUPMDTk: "\/1368.90111?__cf_chl_tk=wylIrIcjb8Q0fXj2jpkTHehUsrjwm0sLPlwXQXE3zlk-1744178243-1.0.1.1-ZU6D6zuwdb1D4bt2GfMuu0e2Bdw1x1Ge6ro.V.2R_ks",cFPWv: 'g',cITimeS: '1744178243',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/1368.90111?__cf_chl_f_tk=wylIrIcjb8Q0fXj2jpkTHehUsrjwm0sLPlwXQXE3zlk-1744178243-1.0.1.1-ZU6D6zuwdb1D4bt2GfMuu0e2Bdw1x1Ge6ro.V.2R_ks",md: "JHGElTZuFObOk5D3CCNlzhpVm4SVXsr3GKoj2UBsL8M-1744178243-1.2.1.1-7dnKNXnIBqg8N7kb8T52RdXRn.QIZS4n4EgJIYlpOma5OkRjfl_dLfKVIDj8utlcsAt_7fF_AUGW6IOypbdq2vR3BRJZ.CP9uh1zxvfgh9LvFx0D90KVo.W.Fv6asvYvIiQj.Z5JLv2g9n81v70fLQ3owgGFjfmA9qlHOKh3VwzqwCGrFSxJ2Nas0cK5aAZ8aj6s5Yv5dx.gzbGPSobS_GmKdIvPh4zKCxizoxeeAwg5exSsWr0b8_KsZyjFBmC1GoCEePb9wK7j8vV33mF1DfaAszC5eryIsWBJPcunBv_UrYM9mxFuHOqUzMPebZBss02vvUxK.NEDg1h8r.U6pJ44v5kqtXRbL2Apcrr.nNeQI6mTTPULaFH1ArF5mPaL7kooGpqC8DxESOG79xpH80tCO09X3BcYzzixWpuIzp2wg4OHCYE6mPQUmOHtTZmarUkFfkqu3tMh0RRIfk7lupjczeFRSo9GMZvaoAQI6EFf_reJdaBsZJEflQWP12kEfq88WsGzlL0usZyg1PqiKvq6ISjMBQbO.wh5kIXE3wtyz0KvXqSwm.yhpdmFgt8emSwAWZsbcrFHMZG6BoJ6wtGVOI0tkt7b3bqWNC1m5RM25qXwRUZ9jYuCLBKhJ.vFD5L2G8GY69BLNzLiCiWf86rAnRgMvPUuXoIYUnVtCaWbqDJC6U9fCKmw4GtnKrP0zp6tW6Vgb.YJ.ryYh4vdKKTUo9_Jvbpz08BnwemMaycquCcpA3mqUYE5Ee9Z7K1Jupb4EyPzBxXUkcfu4BuiEP_Z32zCsAcPxwB.W6NYaYAd_K42YI95n.Q1OkeXg7QKUhD.mWyAgQBURvu.Nj7l9o_aT4m2UcrcwqOt4OtVeaqMNRVWKWVzpvoCVwpY3iEgA3tn4VpoK6oRWehhjhnEINgVYuoya6TKcXnIJDlAOiNlrvfpiE3_4kyNlmtDTDci3KnDgbxUeqTfFpjhGTejzK3dlQiNFU7_JHhiSY597jNwg8L.367E3g4aU5IRB1S0Djgzh0t0jUiLZVFbyndGcpdRt6qRKAsaRrN50wpJkBPYbWryoa3h5n3Xmy7xpC5aQlJtjjUAuJBPb2xI_v5MOyZh5bQ7j.7vYcAh_K_Qu6lAarCLI2_DKSn5NvyyFWbNCrVsGzhIcl8Yty.FV5oeBe5bwoY3HxywFk8ZEbX0Ezg0msnTDwOVChRMqi8r2YTb",mdrd: "rsoMrewtkCkRadWiISv0kFwkKiXN8O1fG7L6I88rams-1744178243-1.2.1.1-qRw1O8j69LQWuJCnAbxt9CFqtYO4QTZ9C8L_nr3H7nTu202DRGAIcYTG1sRCceMvodb9TEJNaC_fYuAuPhq63ZQKuhXIiuPQg7s1kMuIdgGy.gO4avNU8i8y06tuPHqY6agKjSmNuq96pmnaiiBkZI_4f6oTpEBXhIEKOfBizH7xaU1LBEnKo2Jn99Zco9SSa4YuqnU.iJH61JAno2kNZ.vdTE_0837yxLRKOhNZHlgYOCaPL2H4F.HL6ajWHkK2azy_WWAINwIWXNIQgT8YQnEp0hAJs6x1FGzQxIjTwnszI8.D9opgkVEKWlrkGouT.p.QOUfTy6JrPubtzc2GGfyKJ.w4_3Xj30cgRvyjMxP5q0VHPYIGCbF3PqY4yi7sB.2jEpWiAhBNh3BC.2I7n3qCt_95AOUeXEZPBzYQh7fo3BoJgE.IEt2rtlddka7OOqL.c1wtK7UfFZzXTz7AEENP0bBLzHtCfxMaGlbyBhVQT3oaNk.1eCS2FABUtrUgdyHQn6uF.5h3GKUVyYdhy7QAUwbLAV5JPWIUblJZcnKeAwRprT5qPQULebz8X_DivNXmCsKJc8G.O1Od378hh8AyrQZ8JBLFc2nryTzb.5EFBLRLuWRGQl4RJAw3QVcd_TMELgcEK.LQEZppkpomQYLII8IVr316VEgozJy4D8lfJs.buTnlkUFlACAHRIQAjW9UG1ko3xB6KiJhSjJvIsIYkyBkgGWzA00UtyFFPkLtIKY5SfIpJqwKx52R2Gr0CS5ai59ilDdH75tf9TIUqc31H.cqnyRkTC.GB5h7qJGQtv9ENZqSNBPk9ZhimR.aNGIDkDwpO_ltC.DH_wXa57aV3u5aV342c39hxQRUPiSy9VDMbagWb6Qaq5mR_KMqB_AFILP7aMiTiV2191UQ8aerkkf6jK_7iWWgV4kDb76N3Qz8TTa_cE1wLspXWgHmfwPCfKmX7.PCqLMvAhooXRpI3JclW6ALFl0VErnWMNSAuMnCeClNk81zSWpYPNjH4PkjrbmkzPwpe8NtPhYlP4sgXwB2U.tDWhJ4y0N5FxQja2LgoK0OX6hnHQz6RNG.Bm25VT3NzP1JBBktU_XWm3n2vDpIvBwxrK7yImWOoPwJXASXN3uJmJBqD1NKu8VrxBzgFJkCfpHEwc8ZodpFDXrdqwMoEbm.YXJ3bV8fvdIlHpRdCCNGWPysoPDt4ZzumaBNQtpRvUj8eVZLxgBIzTLYxF06NPqfDPG2OF7nNyFomG6FLv4Y53Fw2HYzCPDOFCuHjZz4Zfd0prradevGEOKzMAvCcI1mo0JVEvCDJXIB0GaXl4xHiCMIieU0tZWj4T3qGZnAIQT_v2eyw6qmE20VEKq.OQE27dbnoTaMrZy1HEpzV.OyNwzaVDh9gFApDjYDYkgtSZEBtUx.HIyK5KEEWKWQJxnyYNUomdOn68jCw6vQrOuVAf.OHow_lKGPVGbQEyxKQUEchn14fG_tslZEHtEeaAP54zfQAbwJIz0JEIRngJYYJq2jXXz.Ypd_sa.QpALgdYNf798jN3fle2VNVSwG.CW2HddjH92r9sWdf0d9rs8tw0ZtkHPXy3jKkN0VQYO7cgH4vZ6ry_UwYTC_MhzG.oxJareGowddby6Lvc3t6jykC_uHXrBAJMxzoPFWHGzRWS6gxOFHi7otu7JLMS9VhP7qX5H3GKjFiozS7jwk4E0E2ayGPAMUtrZaD_TsQ7v73EybxsMzD6li9nK2OCdJpg4gXdTrwLihRqvwL3I9ilDJ.ACryXb5w6a7BsOu1O97Hl52NvU9FJ.sC3LGEwDCFXZVV1IXwM1lAybPAtBXm_E9Pm6F7ud_QscatPNDnq9wssOBtd003PNjMtHtJjgkDr.1wuwVp1JknzRbH1EtpcfQ6dIG3mJFzo.O4B5gu8oBfhlAUTgohLEYWUC2mXSazSIsE5ZQjho7sNT8_IQML.j6RvZ5Xn25.lDO0WiEcp0EoOFmSzw0tAEGPfGqiBO6vSgmv1J..y0jwjSimiJBV9b5bxLogV773YbNT7AvlNyBQpwMwr1nrq8wJw"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/g/orchestrate/chl_page/v1?ray=92d7c4435bb86027';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, "\/1368.90111?__cf_chl_rt_tk=wylIrIcjb8Q0fXj2jpkTHehUsrjwm0sLPlwXQXE3zlk-1744178243-1.0.1.1-ZU6D6zuwdb1D4bt2GfMuu0e2Bdw1x1Ge6ro.V.2R_ks" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>