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: '92e164a4cff3fd0f',cH: 'o6CKjVwhV3yP9CLz24h7valbQ4HvtM28Qt101jy1fc4-1744279184-1.2.1.1-pJRjq.Q2uoHkeDcG1PBI5YD4RnSHz.YH20at4.QbhTDwuqQidE56snWlChdsWFIb',cUPMDTk: "\/1489.65043?__cf_chl_tk=rX1CYJGo7B72yfR7yJtLqdNiruLRP8Td77Eh9qk7fo0-1744279184-1.0.1.1-EHUYCoB7rTCut5HFztIDC7z86kyOffzjVfLOLqDK6kA",cFPWv: 'b',cITimeS: '1744279184',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/1489.65043?__cf_chl_f_tk=rX1CYJGo7B72yfR7yJtLqdNiruLRP8Td77Eh9qk7fo0-1744279184-1.0.1.1-EHUYCoB7rTCut5HFztIDC7z86kyOffzjVfLOLqDK6kA",md: "pvzMfhc.fTWKlRpOUIJhU.rtqEY5bXBfKD7vz4nDl_4-1744279184-1.2.1.1-5XqesIPSqyQ15Jq5yYcLJHusQfFcMa9YYBbuJKgXbpuHQzhe4Y4PH_tPzizuJcWOcvmZ5MKU9Jmb3Oj0htBfYYB0KhIgr8SLMeecfcSPglPOt.Iw4TsRBq6ZyjqGrvsHCJAXqA4wMRKIKc789Ba3ruVcQy7Q46tg0tD8mjUMzrNk2vbjJf5zaBKY1G5xpPuErjGBMPCXtgs055Vw_1FpcTCWNla.jyiqjV1fraSD6btm9rXwxRH5J_B_liZ0bk3USBkAq_zPkKpXRM_VrvbbX59ALtpSTzO7yrIAYwr9OGyfZPjXcrLXH445Ei56vn0vDKzxQiLtgWE06G1o1lFF_.fUeYfs061gqbmYFsZl4QrErUx9CHNECjiw3l2WoapO84Xw5nssKrG8UU.PMwx5m.SEaZeUMoYVUya2FZ81SOU8GGXE9hXxLbBbSXy0u6wICZmFkb75WtHstGEJQIrRftmLdKrqxFuD_cXHizKgVSNqE_UlAkwCN5jFzFMrzqSFSJqPXAQvg63wOHY1SMhPJ8aP0K2bPdQ0TAre8D_3bNDY5fLYhx8HwGUHyeWYwh9kOJ7Ur350WoGGUOkPdcLzUaxCeNZkpa.hoMryIxL4d74JGsyGBx.SynNcdzntgrxzIZCtGVWZCirqgT.o3MhSKnxr1ECoryJ835yWNqqQbvsZVFMCjU0fXDfd5Fa_yLAPhFQMpNt9i3EgfXPorw.Yay_nMpIoqwYThMGM.n_GOxyQQwkaUEOWEXLvjPDmioMM_akdq9emRfVSVa7Us8DHWBKUzLF0_KtGzdPXnWclVyNce2kmxyPp2LQgWCsbBIDwq3S.4VOFPOAXoDrlCPLFBVY3Pfw5i1_BGTh_yFQ8f8EnNJwu7bUynQs2KaR_7bBd1oIq8H9BfwHkiK4.2yjSpywwZBWbj9rXBtOw8Kb3TMlmuJHztr6nFq45X1F6V8vb6I6K5i7GxZnya4EOO3mNA5lrArMulx3x8Vinm_h1JWcssxWT1_H8neG15gqij4QSwcRMAI5qYPFGFLrKZ5tbp4BfJiFxA3i08GEJTsRlCAeNr1RpF7OzwppW1iFLUuPRR7CTJveR2siGZnxVlC_AVUG0X6SlLco087sa2MT.zmTT1ED8j_5z_3BgZBwCtgpdeU6H.RSkpS9OtHQ5r1tgHYq1oOh9FQgD9EvWamsDk38F9SrcQX5h.69ucOULOPWR",mdrd: "QJqqUAZ6g3pF9gUzffEf6hb5AtD1kIZBAEiu9OJ8eKw-1744279184-1.2.1.1-9mU4kuqdkneyojkWoLeG9jRx1UaAN7O8jktx_1mNJIzIoM2NSbJNMXBmCZ6hpwODYUZ9sp.FTh_TDlOaD_EW9JA4dLam5d.ebkrBol..0mPRDx6h23J9eA7hfJBfazggskDUdsKiCA2PHXpXK7X414ld3rDjVmb6x19vAK2IMOIGz1fki.DFzdkSfARD._jL0JN1SB8Ifopkab4Jt0O9bkAyR3kZ_nD.v9YnKsTB_XK0gh9lMu8DH_n2H45g_ajXk0PHpSzDbI.jL2firKEw0K7D.OCl0XXXairITF9f01CbtGr2PVemdBIt49uLoxxxIa9zHkKtuoc0Ygu6yuWZz2RE0wCLwQmpe1QF9c6TSN9NgYHw0n2Zmbel5FNwo.qYLoscA2IjC_JAcHC3nK.8SqrYYnWJwWKGXksqRcfPSssUdDH714KQYrpY4DJGDKfXT9gvFz.zHCq7bMCSO4nAlPw2NelBVorRrL3h23VDRgx50krEp7uKO8c4dDUd41bReYs_orYNo0TuPv90NHpwYZ5FPDuMseIs4a1Hd4zP3bCdDysbFBcS8G0VFy5inpVjs1meuRE_LWmnqugwoPVlOfBhJIyUOm3JhrOaM7NmD2WRuvfP0RrQBAfRCq21M_erwMKv3Lg25TiUa7ceZKn_U_tlT3hbpSXflikN27Z6YlMAIyyLXzYWQJ6xXL.Q5qfxwPtGl9lhnaRxgOVxKSI_cjw4W_GMfrrF.jyGoSgqmHfKXWxXZIoh0g3mt0jmPMP9FAWQ.L2DdhDUCyi71BNvWbDOx0NxC4mlNizmZTial6a.Rezc5dqdci7zA.NkO14fV2haCyvte1YasUoouXBXsDaF9LhaHtCJia80PvRAXI1sP1ATZiG6Az4c6QqWKGp5_FNrDln0ZG8.ULyMUd87LfD4N8KkEYleD2fEF7hFgWd2l3dX2aSWSJ5GflA2cYHAJZFCZIpdesNm4z_Wa2FFB1.SYjQhl2k8MUHC._b_GM4G0mv3ZT7TKYXWzWlwTxcO1EXrUqC4MFrhSqHEyfnwk.juV8kPq5zn5dwtFwYz.4gnhLJCBxmffSUf2qC1AGO5lCHKihc2a50BBa9S3K3XL4bhded7mUqqtD9BfzRnOe28s63qrsgLs3Sqd_XnvrNkz1a3AUCNn5pOvDWVjgVanBcJHWitCpFJj8FNbllmnNVy7pVrV4aoMCSRxUexQpNRmN3TcaEGqdqZ9Ykui_x5ASJFTtZFlsiY4nUQFA_K.Dszry2ObZ.vB7P2yLE_5.WQmcMvD3tVQQDjpj5vbhoK2Ei7nAQ1zt.tgeHovpVjdBp.5i0PA38Gr4MIc2hRLWOVJZO06tU7fdfZwCEuQ68Tx3rztJ0ssJ6Gsp.ZaBcwMXi2pv2WHFKLJefBuBpHU7KJV81i7So4HxP_N9EEW.8w71h9yNUHLuwxpCJKcomWXvepwpvCg8nfkuxrLqYns2vyhqclc1MosEsR.gFZo8j6t5ez6igOgGxC1TlYcVJtt.h.5jS.MXRrdbmxI6tGYz3Qg2sURCO.yLlFyn0CwDrvtyBIlHluqNQH5dmcMd5e9Ox.tfzSxfIt7otnxHnnygR6nwa9aebKYz2ewnrt4zlXBszVVq8PnybSDFPBk83NMuOzNigaR_F9HPPCMw9_nzZGBRX2uR1sImJcXCElIrIC9DhIYQ_uMohDSWomrNJdjU15x0fnJOmefasjj3_Ue0H9NUCblxtWt6h705w0F3Lt7YCmYmRTJQBEH3wUjvulK4R1sqohz2qNgDEefgRhxfI6QAlK2y_.0CGDbE.k.ih8fchNSesYx0o5qnIpII9njJ0r0KD5pEYP3xBbTsqkvDVpo67Qjurbh_YXzXvwHLJV5UFZ1K3SQo.GIZe4D5K_wY7.DSuz05BnUHNA6.8CCY0ZPSroPh7pxzrVejLoWCygQnn8_p288iXVK2_N2CgcHhrXnf.0lHGaQvfokE6h6nvZua_2GfYO_smSbv9OgYwxEYGmh1T7bn_oXhTsawP9I2_xZDlaP5uZGgXVVxzx5Jt."};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92e164a4cff3fd0f';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, "\/1489.65043?__cf_chl_rt_tk=rX1CYJGo7B72yfR7yJtLqdNiruLRP8Td77Eh9qk7fo0-1744279184-1.0.1.1-EHUYCoB7rTCut5HFztIDC7z86kyOffzjVfLOLqDK6kA" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>