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: '92d4885cbca9ce62',cH: 'U5110QxVEY45o9Z3JfRz169WkZfk_AY3wqm.VW.qpfk-1744144332-1.2.1.1-J_soijXIoPm_Dg_ikg.gfr9PArdR5bJKIBKBAYvRHydtzZ3n6iVzrTVRt6qaLJiO',cUPMDTk: "\/1484.34139?__cf_chl_tk=PGmViHFob6b1r.JmtLeaRAuW2mA3mytQC1WC9he87bo-1744144332-1.0.1.1-sqxHdm5n_HX1dByNXO0ot_13dgMe.Xn6i1mOpHa.QMA",cFPWv: 'g',cITimeS: '1744144332',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/1484.34139?__cf_chl_f_tk=PGmViHFob6b1r.JmtLeaRAuW2mA3mytQC1WC9he87bo-1744144332-1.0.1.1-sqxHdm5n_HX1dByNXO0ot_13dgMe.Xn6i1mOpHa.QMA",md: "LOvS5i59Z5a.ziNwY66q9ckQxIuIXl4rahrzP9ANFbE-1744144332-1.2.1.1-T_Vk4BkZWxOfISt49ania_2o9FHsSOcm6Nb3bRGcFEMlkdmcZbDF05rwBakSYJhoQMGdf1SnhozoeixGBT4G8LiV7JSPmiMgtGRVD0M85AwJ1Rwzlz8ceVijQMQXfdF2qTof1Q0AujRNnUpF8C7aIQrxf1e4.cYdXISpFj7gldNSEDhYjW6.AY1rfWmMyK2lCoAcPRM9RyLf7.eGOJiCxa.bAMkP.iUXFfb1WHaotdclqeBrW21QnU0TX0VeXR.TYibMf4O5UHdEv2gZC0DT54ZEO8vqB9kYxnt0qWWkLjd7dYColNTteDUC4ajCXmSefsGF0jyXPhTQiD0_Ixm1wi6GfvAC9jNKONmvMwfl31t_gquoOF6LTdY_SShxhp2BuY91FEmhOCJimh7ePf6NIM5D_hXpJx.Pdwh8mgrmN3POFUzZAFWp9Xl6YAf490y5YF46UOHYEYrYgbz0qPpZV8sHLd7BxXMMMamqtpBWDpyx0rNO4B0doZ8GdthqSD6gPl4w_UygkOCENGNuIWWUIG2a7T11foDA6hythzsjAtDbnO65sERnceh0c0FVGUOPvPGmjZQKqfDcss8BqivOxc4UAGm4e3OybVZbKMeZEAoT4xyX6jB.IqaOBCgb2Nfn3.jiwaW_083.60qsZa8Ht6.wc8waGsDwt_v7Q4njwEJx2tsLF5d6lBLjp3UuHU7aOzPpouC8kcnajRXzmO8Ftn641QIk7zc.1aF1_wo0Fbe95mavDeFg3TdgX4IhbovWAcCV.eiTSShhFtEjVoXatF3mrjr7CSsBGM37u6M3PAKUO8y2TEm7prIVjYozzY6B1.zUetLmlfXKBI9ixgODGAWnEZ0RbaPifa3Z8wIxx39YRV_OQGlGf3JrNf9q7beJUEsDqf8txNmw8ppbkaYSEne7ESoWVd.HxprHXCYllOgDBY2ZO13zOrws6jxPGAgMxqpeJovLwCuWPca2FA1YZZEMszEwy07fTHDpgYrczL5cu7_Wh5Gv5G7yn.9rJCx_RZuha0CKk_OoFeux172FDZ7wnP9.VbXjd0uwb5IkC3E82X5Y4IAzDeNCV5LdKKi9STrfalE8Ak3t0sM7G3s9c8og00hZ39Izde6hN.NlUP8ohph4F6xEPFlxOygyrZwRFlBuIILIu_2SF2DTDUX86NSC_jKelkhiZxl5Y3Iw.Wmfky3v_XWzWFPRwsaKV.2D",mdrd: "9OymgQeZMUs_wkflPEfkOYN1HNgrgggexLjS5yk85FU-1744144332-1.2.1.1-_W5uyVBdpR32tJ4cTJO9Nvqm8.FlIFzxmcFxE3hgEZcxdNQ9QNThIMoOKLzrF_T3WZgIqAJD57UoIz6uXPqUsmawMC4jCoKCU.d2B48u65hiy0OxWXoBJri84w9.CjJbsgkH9i.OMEERkwpbiKCKV5t6SRcClaLxBMfB_KlvDK98mOfgp4aOBWlP9CC3Ua4PPgMhTzw9n5A_8w1.ZzDn3e3kwwnGCycl1w.d2jkkQCewKLSWe9AqDDuzjIaN.1ypGcZW.igMhYW130fxx_wjyu1h8ar.ufLfRGU5_vKIRXjjnquRnbw_Q6pUxtP1LBShn8ziNyY3cvFuJhVYoxW8WhlmQKm7IxB0FQkDoZLCgKuRbymNBvaUWlKaYy1ea2LKk01Fk0HsBgamDf8pqLnPcCCYj_wPkUypoWYyo9JudJ4FbXvzZtQfNURSQmS4zj5._VNnpbPx4vFMmP7.2KTlDyn3rfvx6UuGknf7VwsCT85VqeznxX3EgH3KdiNLL2yqyJffkGsuL9MJHZoBq695dCe_jdzaitW1kzgAAr3bglbMN9TmERrtB_pVlmaz_sHDd4h6FE41vZqQWjuTlDe7lbsfWDRL3eC07CZTRjel3SJtMmu6Wh.Hh0gb_XCd3x1QeRzhttxFojVjBPJX_XpOxvk6SiTLsnAOwPqohQuqPQxwjrNraoti.4b958tx5NAVNOkLmgkPrzfrIcrR4.8TEZMn7JF3UbZtmoaay1R5P_cg_13xPqx0200MUnybkb5lKB6XZdq7nQ2Ykc.vGCsGMSbiRW53.YDJ7MLia_ub2MjA6gDV_ocNcFjM.o4O4AeWaimncDeaucdPlwxgGvRmwaMH5A9tst0Gd4fx09iHdtuc0ncP3tNjfs_5NwQb2WSNRQ8.uRkDksc_hRqqYQKTQjYXjDGi1U9mWPqjYBAbt.TdDNlwU0IfpYFtPz2L6NAHnn01IKVxUQyFLGHP2hS2sw1Mc7vjGlU8vM6S4BOL0mgClUFNEWsoOtG2yTv5757m9EaMtGaLWIdoQO68yxBSRuN12.NB0QXLc_3BLpw2Nri46pAlK5Xf8GGr0JR4YzsxaVs7vcul95JlQ4rZCLlyVVt.tlcQqDJnq6MT8viGlRNtKz2SDDwRWtVpcYYOL0WS8AhvRzZ42h8WjxraL0Fjr6bbLXHqSotEM3x2_L95o3TUY.x2xjfXaW5Q49yN.pZocdWlFYrKjAKuKava2.IJALEtYTxUysMcwm1fyBYXLYJoFWYoC9tta0ociVJnhDbnMBDBt4qp2lgdRgt1mAhxegSu9xk2w4N3_t3Rhw8MKP0WWsnJkoCEnBnKHTMUYy_0szt6NL__2g741jkX_nwLFZHYVr5VXHj7mzz6XVI10J4Y3DsUl1egDHwOxv4D3zIE0vX8Fp_Yfl8ZgVOcUCeL3kATvloDkO6nzWC2Ceyji3Lc0CO.uLH.UmkVc3s7gd5DXymJG.YVLLwVOGztBPdmX81mQ12HjQSySvvI3L5ciWrRFN1TzJQxgud.9x8XAA5WYfm1Hu5wtaqWICp_SEkWn5lGSrnCwO60Ej.vGvC1FAiLCbO2VcLPYZ9CXPOai4XuZY39LaisvL28o6WM2eDGOhtI8NHL.QctKUAT1NupoiHjBCweKtdPGdi33O1qNpOTCS3JBmb8Arq6bptdc6j_YOo.sHb39V_OG51b.fF6XthGPzClqL_L3Mhm8K9XdTDnCOeVUD8bnvgV5S98cm8q1PwIIl_1Y2mO7rRi3ouWxZrwHZrsb7sM.0VfU5NyiJo3ZB5eewfEmf.qfe7GyTz22ND84v2KERntciMTE9YSL_mrjlocIiUmj2u.A1Yxz8qx7ebS7gnSQZQKiD0lQwShlQyrrZyIRCPc3AtqyUKBW.UvNEvnYZO.iGq80mXJoK1PP7SfXJIodUhaYEev8.NEmKvrXXS..Hd32V1aJfePQjASGLujrjoEzMQFyzq7pRBTzDhrCocbfXxa_UZgDLjgyGrC_7twrvs21IAoD8cRLlZdOtF.53MmBWRf7yENy9p."};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/g/orchestrate/chl_page/v1?ray=92d4885cbca9ce62';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, "\/1484.34139?__cf_chl_rt_tk=PGmViHFob6b1r.JmtLeaRAuW2mA3mytQC1WC9he87bo-1744144332-1.0.1.1-sqxHdm5n_HX1dByNXO0ot_13dgMe.Xn6i1mOpHa.QMA" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>