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: '92e992112f003231',cH: 'ZyO.rEg2DMPkrhK9kZIDWW.u2XfjSNRKjMwXz7uhSnM-1744364930-1.2.1.1-FQofKYJrjlJcz7lzTa6oReFJA2GHI2SAIW_RhDVZbUzleYEvWIWEiYJ.sbJSO5.1',cUPMDTk: "\/?q=rf%3A1523377&__cf_chl_tk=gAU3KIXrovgiJzIwb0HWI2qLkoOwwap4mA1XWPEpe4c-1744364930-1.0.1.1-RDxBJh9nQ4J3LL.sGQwH54lfRkhIIZLzoTAxOsvilms",cFPWv: 'b',cITimeS: '1744364930',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/?q=rf%3A1523377&__cf_chl_f_tk=gAU3KIXrovgiJzIwb0HWI2qLkoOwwap4mA1XWPEpe4c-1744364930-1.0.1.1-RDxBJh9nQ4J3LL.sGQwH54lfRkhIIZLzoTAxOsvilms",md: "_Cpfl1vrW.gB_fbpm3WAbnxJe0ZuvlGG9ytZOe4JxcA-1744364930-1.2.1.1-me0BnH67Eq8ebGTrAU6FmRjxgjWrDLps4hQrjCqg5sycBAO6OW6jfVVomau_z_h6Sb29GRXJyyCjE5RT6Mfob61I1yNfL3rh6YEtRZe4D1OehGQq7Sic13W.3P12Yrnr24hKN8EE9obzA48rVHfpKGjLDBBskUCevuNJQHK.TxSnxUli_qsCzCtqJYw9RWNKUewlfehC8GDPqOm4Rk4_ytJbYqyVS_loQl1WTrGCBuJ0pK7Sok6b0sXpqz2xmA.NLzky6PPhOq7VqcwmKWFC8LR3JO5MsdLYIlgF3CP1AOX63vjySaCjug5od.6el222PNx5zYeQxujYvogE8pj6cjmFJV5j85i_ushBxFNCIjHgeJvtTmySri1_1b7qc90AnDKX.rzCBKOZkjccgu.n0vftCjTMsW4WnXOMEYhGFLNisLgEulx5COVC7jpMRfN1WfDwAcqPDolhiMCTbfAk8VT2fq4v45y4Q0drn4HaHmKcEqc1QKu45LCVzXmtepFLhNgZszdapYMwB5wEG9Ubr_uyVisrgDeQMGnANjqbRoWd1gIWwIRMlJQ2RuVITSyHcNxhrVUBm8dzBsEdcwMbf.Vj6G0iCrQCqaZtsNlluYLEsxnIqqO4CQHmWgx1ectt3W99lWLW6pQ2ZwNu6LJXateMSkujNExVJ6pi1ZUhAEdJVfmxzTSlwp5jGflLMEZ7h_7QABZvrUsNFKpFHttj0FrpmwLU6Jw4HTrt97dkWs_MSeF1FIno5kXF5qs76Aju7KnKRTRUe8c5MiHV7ou2GflpKJOxv571xVx1TjVPXMqkwNKq4kRqo1xAnuSfHb7UPzYa7jieJdY7HMuScwBdfSsIZUkgJGwlf64jHsw4e3MKTobYIc8aCpzjkjqzXByOvAwp7jsf8JObnv6.sG3.rL8U3Lg5RDN1YxYSEm_OY5zFxCdl7gi8kQhbe28BEO_A6S75Zy7nAY1n2L4QCShxDO4ekJJwfUuJThRpknuenfQYYwd1zagEPwJsDXIcrnU.92fKDmuFUsYr0NeGaTv.eI7N9Q0OYPdySvky0hkNqHXv6ZJGC8MrqI9zMMhdz9LQw3WnQrvJoMCKo1E0QOzHERDHY7myzdFdvkFf65072KwWbzlv_VCzCaxSOeWclyhKjbzRx0Q4w5mAygsvtB7vK9SI62heqxDJ4LxDiXk8AqjQRjayTGirfzQB4KiA6cyu",mdrd: "tvdmLrWkY.kxnFvdxk1nxpUIA4di4ORAL8GtqXfUrgk-1744364930-1.2.1.1-u3CQLWKlei4eKa5FhuF5WjIPGOJMawG_LICBGghQTM3kIunb5GxtxZ8P3wXpgEDXehWQQ4hmAUJhFTduwWmcLNVKDdW2rYsT06avnjrueHjOe9QjzgzY_tasEkIDmIQddqJHMSJXjiPdoSUJ84yn2rDQTrMblhuLSAC_umFhjkxtjUFsneb1d2gFAuWNMGW1D9BQP7Hd7x_Dc5F7ZGKQ9MK6EaIDKHHKwS2TLaAvESKULOvdqhcZyTR.mGvnjmCQfrH7zQNO5NFdSX5QX1B.ZHMscfTWOFgr_0k8HIwKZmHuroBiv_ZhgSLTk9uwqiU12CXODFgxjo4LicJ8XxNjBPoZXeoj7URuy0ERqSeqLy8nlq1aqNfO9EAcLf9d.9XN1E7hVLQgbVJWrctPZQggfQs5ABv0Vt2cY1AhJemeZZc8s4dYuDLS27dYs4wxerKSZ_ayrVvRU2y0q3pUMEzkPTvr5nL0q821d6lk6UgD7DOQNsq6t3aBBD1hxH_nhb4p61NpPsCnegPS2f2M4GxGAXEWlKyW77lFM2a.7HK_EsCDPTFSuTnewkRso9sQz7r5p7u5nll92EB.yvs8dntQfZNTe6INlFwbVp.iZLJeHw_ujacfR1c9.eM5p1MvBhj1fONMm0QWbqvytEeyIDS.kJsDkHRGcKObctO.G73TYHVH9J3oVYtzDR2RvuZmS2XJxbSR6fy6wde07pmRQrZtWNz9sdzVEWONp0jNOriff2qhaiN5XrYOgwfyYT.12XOkHSW7b9LetWdah.zBFQ105ZYQOfhGOqjuq0VSYcyHnbsBcthV_1AWP3G5Te3Dng7Rw7IEvnIQCbAl3hqO9BNhdpFruwMNq7uk14auN2s4CelX1pbLPXh1_Up7YgawUnjVkYknJicH53AD83SDuX_UOYemmnfijC3m7CPLwNk_t.YvQH8g6lNTXvytD8pVvP5oBzM11yAcgeL_j5GlYJZsy9LDxzGCWGaCHwaJgp1fvShtfTapoesCm7_tJonT5ZapBN0fdnJ0XmxrKGyTbG1gD9jKogp0ErXyF9kLNMp3Sgy2mT8P3JfW2XMTXhXuwDBM2ac9GmF666oTcdFrKF6oSRXzuhyCGU6IdgjSZyoLVZ5SWvsRItQVW9DqNiPspCREpsGbgZ.RC.COqwLI33xz6D1i3Mdsv6ZmQ_ABNcJr_W6sXM2dRu.pvElWcOPP87EH5hiYYkDAGK9VwIsJgQuU4kE_eJemvlb38a0UumntBJNgHnAv5fK3PbVYHH3P_0yBpjejkEvKeR7Ewmvs8.VQFw6f.vd_GY3bNbdS0nbesF2CUOK16_tiigM2kbnTTqgGsaH.dVX6MFxLPhHLBpL.nRLqncHheAVvRIHX427yUp5XNpvOJwP0UBuyHgamdLmrziuc8boTvkp2lMZOnRqGw6CjVV6QZlzfrADbcFfbpSJXQoy5irhPTIkB3udKtfLVd.pU5uYI7oXEbiYPRGOBLwTB3ALUZRwUtKF6CILox_Tbr9_lgksGzWRKssyDMtvMaQqzb7xhe1OjlzknzTjfiNfcSbzBb3uGLetcFybc.FuBFXsF.yUQROdZVf1L3HO7Vv7s3S5fBoHqV3.cqABbb8a0qZUVqgiqaKTlLit8bC2LqIAsBGYx_pcRK7SkpIH4JLxaMo1G5UsBRcY9SO8I38EjdnFJ37itiMt2Kl3.Xd72QIPKGzQ6ip8vdhXJ_PQnx1CXUdNXPqDE4O4ZjnpM48Qq_EB7uRtRgVDVnb.EKS60BUv27SXEW42hS.ULx6d4xcCNd_.iQo7cMy7n_IbqA4VnwvfLsBmWL2W3pIhxSqG3O96R03YOfFGHutCjOQiW2Pk59lPvs1QxBcY1Wmc4s3kZ6lxKcINmf7jUKezKjQuxVHdh2GqP_Rqwz2kCRfI_eRtqxBXMOnfwighAFjhDs8iv2TlV4GoVelB03WsnD2vnzdID89Tx02Ebm6OGnobABUWbr2Rr.3z5N_rDXae8UTdoCdaepHe0rBYzPR5Yx..FOSryz9Szn47tGuw9UO0W"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92e992112f003231';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%3A1523377&__cf_chl_rt_tk=gAU3KIXrovgiJzIwb0HWI2qLkoOwwap4mA1XWPEpe4c-1744364930-1.0.1.1-RDxBJh9nQ4J3LL.sGQwH54lfRkhIIZLzoTAxOsvilms" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>