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: '92e1642dec7a8989',cH: 'K0pxGP60RMIr5qe1C5r5pgwRkY_8ttHbd8UGHPLTXTQ-1744279165-1.2.1.1-VuC8AgR3ZqWj0_tl4_vzCYI9fd2e69VAEdebFU7iEF17wa0WRKrr.kFsdySpzWXw',cUPMDTk: "\/1364.65135?__cf_chl_tk=2q8bbFZoLeIb8SVERdAHhpZev3B5ODUuWGgRAos8nR0-1744279165-1.0.1.1-ivKEdEQJsa0YX9V6b0YOZVtgLYNNQ9apndk9kgmPAnk",cFPWv: 'b',cITimeS: '1744279165',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/1364.65135?__cf_chl_f_tk=2q8bbFZoLeIb8SVERdAHhpZev3B5ODUuWGgRAos8nR0-1744279165-1.0.1.1-ivKEdEQJsa0YX9V6b0YOZVtgLYNNQ9apndk9kgmPAnk",md: "EN7tCBsEb8X0Xeg8j_.sGGiFfCpqVYOH4SodbIPyCkc-1744279165-1.2.1.1-o9EDl1m1Y9cdlhHuGYcoC1SyLT5sRm1ZYvdyCk9gUq_IdK3rIV8G3NVN3UAaY7mZOAnIPkLZZBQrkIUF3W2vufXbnV4._3wg9yArNC6E4ya0LM7RrIDUSFbb3f0KwAz6p8VUgIgTUnWLYBujI1wKGrhBaHCrm3bjF89rjNgydm7rQZJGR4bQSS4_RiGpBfD2S5o2_wp2PeJNW_VmJYDItWmmtzN.F1i4d_.wQpdY4AYtfm907hgNGXsCoLhBA6QMy.KvXykcCSpLKykSK2bE6JKsXd3.6wpRO5R7n_qLD1vTxec.pgpXK5l5uSc41izsG.CygUlv5s7NQuVYnIjYpU.1xumgz6r_KqLOQFEbRPhG3al_iwGHDcYd5KRyfI0EOrA83jGGFfExXzIDabBBbGnDzln4A.uApsEcSo.OJnF_2spl845eR3pviB2wV9kgCgZC9gIU44UCJYmM6JJxJLkbpdGThKMjkHyHGt2CWm.QruY8EZOEC1ZqqT8ilg3s41AGHAb3I.KSX5Qndk5A26yyARWY5Cx_RrwVQTF4QkI8EA_wBEtxWn146y0nOSuuutXaauTqQnf7LplECXMzcMIjCazlZUSnRSLOCGy0qJABzmPKlH3akaP15Hu_t28k8ssVfXhLc4HC_RE8NAOcDsWyZSeCWAzdR4EnXxCWKwWb9riX51UkK3ATomWgk8NS4sMXaDZXEQEtQ1ccT1XnpE_x1QtETVKE3E6mbUZo6CaYqt7LiVNDH3.TQ9d80YNLgDE7HSolO5xKJptHKBa.vxdzGDh91uNd4dG7q78FHG9L_u9PUJzrCRCo6z34_fcQ0d4Ak7dSQsaOvMK.YoUZYGKXGcAVSx5KC3IC3ElpRSpARAdWrSsGtbb1XPpv8M6Y.e4TBU8GgAAFqFlmtlm9C07x8Ydd6iTXKVfuwIHNemjTmFiNEA7gCkf0HM9H_fKblg_.dH.oYOKlMdrEjbNDeHMool8401A5ecuVo6nmoT67OtDgXhrdYrmrykYQnxP2LBEBQdqMbUgZHcWi4Cnix6X_hxppCvY5czkS5lDKSvlSvzlR_zvvCgtRApg._5CaxVya8NpzcxnRQ2FfMjiwiM7Ly6r6NuVHawazdZ.7Yyu7kWq5Fhi17vE3_GKVUzqsNg8sIlO3PWbfwYdDdkW7j.BwWxTN0NvyS_Ub.C_LAD1Y3aXkJmSTTCNZ74IRsMW.",mdrd: "pz0pC7GAMLGGmlhbDwkWwbpzik5w_Ws82e5tRK.uSLs-1744279165-1.2.1.1-U5i7x21eOq6RzUvAuxV3RNAaG4CvIbJPqawlSYdgMgYtOnvK0TjjQ32x6zjhaP.FQu.Ht3oJ2MvK4BlVR3TqL81kLYm2kssMqnvMGYLpJ0xCrjWyXfAVgcHaOTKunZx0MJTaX5zqDbzn0AQ9Qdny1.8EAvvewOZ.KxaEL73INIbqIPwpiwLc1KlDRDAcJUSBZ8woxpr9Ofwdi7W4eZWNqw5xXzUcKi.lhxPuugIimPEo65DIEzdfZOozwOxLZ9wuDBCpwh2k2dhhGgml06nXRx5v5pLiHJ0HYLKIio5O5laqDXIUmc9_FsZh5SOgnTpJQQ6VtCTIsAZPrQCkp514pT3yOpYyKTmX8QrPHH1WmMZ2NJ0rpl0H4RNI4hfBC11sDZa_TrnUey2nWkbj6ctfnQsGsgsTpFLeIXiyuZiOBu9Xa3ymipcRR.PS2LUrFIpN86JC.aJcdfDgM2mO15DQLCtlh8VXbldKw1T82kGuUWRbici5gm0qbfCKOMIlU1J8RsaTkWerK.glNzXQ1hoadtVVPnjVUPfRt_06jbqrOkOuJWejZxtVaxL6Ht72HlqF8hQ10El.XxcnT0btxzHzfIFBJdofVXd6T6komdAWDOG_CVhGcszy_YX3eIP46Z1tvSCZ34sbL2Q.FZycDGf5UHCZpyF_DtNajGQ5W_BwDA5uSyfSeq8VNvEryq8zmanSI7iAQC4.uFBoF7jMQZCRILrLoHZgBwRJxpfauqmWYdTm9KdH9Nq4vm1eV_mRcKpER6nS2hNor5d9DwQLrOmvmAdRJA8d.i6fgYc1tyQQPHu2EyW5A0ggHCMHnUXtF7fmMX1UfXWwVzyyZX9cx5GDclJBd5qGMRWlJafOKrw0qTpDqPSGUtzsQSzt.gB13dEX9Lldok6kk2vnkJj0GGZJOj7Q2C0A38Lpk9tWOQNsFNX2LTFCHEtPCHpaNeP5Fp56nmAqme3C.sEJoDN7rudW2Ro0xZdXR__kVAhZhuvWiXcWFWTioJrFa2jDNp4xabnf33BXtQub5our4pc9msxfIc0ReRPAi4byY8.BjCJTL9vXRCbRtaPz7UZmOgnRkK4iolaYGjApa0UkGxMuNTOszfCWp611TnxKn71l9Mtt.pIcLws.hqhVPyI0ppe5BByIkrQQQ_UN4fgGkC.qCbyho2bvIITXl_v1mxhKjkISdzu9x5kqB1kcTxnzDQlydHQMAbxHaCn_L.PzqpD_vUPhctrWeBartkVXQ3odHdhGXV5TjON8hpTqEFvgmCdRKPlqhAFeSvTxhB6WPYhGH1npctfV3kLL2shHkBdOkfJFJF.Cb15y1ELXNlXzAYQu4r3VADSV1Uh9oK4Tqyx4mJjbQciTI.ON_WN8iLYnaKOCUpzwIXzf8EUibN_IKmxSr3Wpo.vQODSTMtQjfUrLp3mT3KzXaMUdpV3_mv9iorBnzrgEqHiLqqJHApBheQHQoQiyTWo7M73YKwHHG5uT0S2gbPzogGibgLFt3SzNkGIe0wqVTYI5xfcr6evUExgn5c7judUIuKkHX8ICkZfmPEDvhMuHnXB552npvYCBJCveldTLRbB9NbBO65oLIf8d4NuMngg1jSTQ_QMZckhA8FBh1GtxHp80EC27U34wm1vDwz7.HLymlcCVb3A6SRzAuUd7xVCFE9JzTMXU7mWCLFNk7pJUjwCXMYJSUiKlmWIa6G_K5iqbj8SiSmfjUVh9OXS0lGiKm.jIoKwb3ihnke7e4iBv5YUuh9p4gJ45QrW1fwmepHzkX8E3lEDSz1BVO_sZmkatSseBdPmyR3JgC.yFHj0hahfOJuMlspQ60aEOHs20szXThTshDAbGDyNzti_1STbNidAlFhtNghR23xOGk2QC9BSnlosSYF3sQJYmSzOI4TGXlbS7xh2z0fBVhxv45O75Df07Z1j_VpcB9xFP8jXBmNYiYUugkijcBTKB9My32L0xClx1OLk2X19D7QWhv1BYuHgW391RQaeu47rY77j4UtZF31JOFuO5FV1eZtXp2wIT2fItKK5HtEtdn9w_"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92e1642dec7a8989';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, "\/1364.65135?__cf_chl_rt_tk=2q8bbFZoLeIb8SVERdAHhpZev3B5ODUuWGgRAos8nR0-1744279165-1.0.1.1-ivKEdEQJsa0YX9V6b0YOZVtgLYNNQ9apndk9kgmPAnk" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>