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: '92d96daecbe09b93',cH: 'fSqZeQI2Z11r0wF7ANX0k7S4YPI7JEA9Yi5Ur8BES1I-1744195668-1.2.1.1-Wou5epDy5F36EvniRy.4WbAolDyF8o8reUHSyJ5DMLza8FTm_eHNyZ5PZl1EBbGi',cUPMDTk: "\/1417.68142?__cf_chl_tk=xk9wLt3E70UBedUwlvpfAMqqTl7ZrTizwiJQ_pJpif4-1744195668-1.0.1.1-euGn0wFU01omqVQ0FpBqJ8Y6cj5gasEyNK3n6SYwQyI",cFPWv: 'g',cITimeS: '1744195668',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/1417.68142?__cf_chl_f_tk=xk9wLt3E70UBedUwlvpfAMqqTl7ZrTizwiJQ_pJpif4-1744195668-1.0.1.1-euGn0wFU01omqVQ0FpBqJ8Y6cj5gasEyNK3n6SYwQyI",md: "bG3f2d1BJUMyh6u6VkSbHQVPUnr1ZUJBk4OMCAM7rFQ-1744195668-1.2.1.1-364mm6TCmr6_TBenwIAVC7HqzWo9BhrUmw2nJIFZWXSl3LaeMkYkIFxMm6yMYWAEr8P0Zm78nuWu._zGJxVm.O2LHbK0tq9fVZ7ZHgvKhbxnJUwJoX8iv_bs8H9v98VjDVV7waRvheKew7assBfji6vWlF5_OuLQp5gSkK62srQM8aWcK56D3eGzFlHURxOfzw2MSMrBgSn1idfWn8sU1xKiy5Kqi2T__gdilFc2.CeDpPk.TGMUt5jdGxNyAbtKbUG4Sjpucpzh_xv_dvyIOKosyO5c47YGo1PFJuuqOAijghtbntz1OXZZb3pPAS1cOC_XDwR6KCaQD05rPf6oBxN7yIWqssbY9RVYyCl2wB1dcm1VVqF1DNdhqI4PqVnePJAHbAkm1ODu6Er0F2pdiU8WDojscFwn9uFlpBd5LEXD4QQF0ByA4Q0U_LIevyd0DYSsOJZxxbSD6ia9aVjc958g95v7WUuLunmeOn34VQyM5DOtVw9KnyVd5A7vw6ZPrenHMq3qrWWbeGyIMbsYJLUGcSZXevZZEvv1IOnkdMMvkf7lUkX60L82i9pscd21YNsTpnRGkvlx3aEO8l.B_TCbJc2XIcvBErxM3rbMflQ_I7XMNjYknpJnjOR5oC.w.kTL7m1Mhrp1XeiW_v0rctIICuUHFDN2tUKp620yuJAOoiIphxm1OItwDSYTLDxq_CoFo.QzjSi.ZhbWVkZNHBtJMtaB_JUh10YWMXL5xKEMzvcHxYDejt88iYfY_j9LSCetyA4JiiwciDEkiijQnsuzn5Wlxe53L_YbgewphK4ZgaOqV4k4UlVze0SJAjwtkxN_MUSKj1CWyBSwq6uDQ7wE3TEq15sn6E.9YBgbezIidQpN4670Dn4Ydfnc65X6swuxUuA6nxvzLTMxPL0B.pXqRrMIcoOSz3ojnEAmesbGfNsoGZd65yyb3PtIpw1jtgS7Ve8jTPWuogA1UUi5BC7QK.qbneqMAKOxD029IxJTZ65nIB8vmo1uD_i6EUskrksuHIZX4cL0mugT1qJWZJ8acD.CkBQ4qbvBQlnuxZ0LnquNygbeq1_T_4oit5N9lGeZwNBv2eZpzFnyyfqOnasri67espTnP_s9ILh26gY3YMLAp6rLg_re6.RvXH2Uj6sKP_9yZxJcP4JExrYcqw0UKOXISXuimgpWvPK_CFISUGgdjNA6S8_Xq3b42Mt0",mdrd: "Tu8pOXKRD.OMorKgaftKutWY9tGzEgzyoFlSXrgPAwU-1744195668-1.2.1.1-3iP30xGN3kvGWoabej6jKZT0c1XtggqoIS5PnQMIdt3l6eXX._zvU9nWUBJxJH7wNMTIWXdE5KThzy9srLHp_MnX55v7gUvDWz5G10VYGFlJ7V0lzKEURBdZl0gxkkkj823HMVw_TZqzuaZ8Qv9PXWRi._an9mYgZflK5rUbvRVzG.SSBOU98igyRLdCJWQAAoUhFj5ae9l8m9tcHib5snK9hkwQkIYKaFlSMGGDVtrESHwMiu__LeNnlRek5k0.Nj7vw1pYagEzL5kh20AvEuy36lSo9Lx0yBE1.CVlvGwDjBWD5tnTfIOqEmiHK3kSlGspBlnC7wPnpzRt_3YXtyikUY996XJHModeBVXz2BWJNWpgMyO9bdb4C1wdwRzBb85IUZpWSD29vuzJrFzjXy7JYg0Pc6ds_6XYH7Ni2AY5yGE2V1.w6F3g9M5VWTyFJ4pdIwdmqvQpvxZ6yuWdsSIupC4.J0uJgr20mmJH5YIMhdl8r4q4bSEoXDqHzdG9ie8B_snewGrQT._ZcsTpqiXXi5YirHAA4f.2UBsiSKlzCIlBXndOTjN1swV1cJv2sm3.sQKlwfuYqEZ_.2TQt2tDewuKTIwF9B6DE0sH34RcqqYctM8IOW_G0i0R97.LHYaUAdBOGDVJ7aG2o41vGMH_0Mk7aZ5ZQ39z75yQs5FgHZ.EhW77fWVie7oyBmbGaJh8OR6WhFGgfYmD8z.d15OgAe6eZ2kPMdhypm6OQZKfGk9meO41aznHjOF3Jg2VM6sixzLNaMIywN6YvKvzzYRmwMBEjpe5bEne5U8nN41mO95gUMLeEIFFS_SZV.1ODa.OCmhmVAWUJ8PHKXO9umfs5MgGH.OJlg_iApzv0eCfuPKE.mu_CYlLvcmdVJI6pdRBxzJVkvB_ZITpUqOEipiJ2w5uGGR4OWDY5.eHxNBVZaiO7jKkyrj5W00BRIK8KhpK9Gh67IHCxsjS3Qnbgq_XdSOyjJPsHHlCkdXoLgBhHWCx6cyIIQ.aqbzyB.9z80D4A1kI4uh5KFafXXk9r04lTE6RcHAKUwIJtoUcx72A3eyyQg2YmFwXGjhgEOFSn55zAmn.E0EzU4D5YybRbhFEih3vbZk2uHmD7XQTacmf_TRxsTWBYzISZoii49JfGSGo1GTcKD2foezCegg98V9C_9Wvma8IcJ0QG3StigTw4vOnKrUNtTEy6T1TlsbHsKEyv98S2IwtqPn9YZZbLH5u6RBMKEqKHNjeWGBP6VLxrkTAej5fjh9c_UkAekpRpnV9oe4u8UI.ntaTYATV4F_Rjd92859kBBd5QN7LAXz.PdggtABA_8j9H7AvOEu11gjCmtPM3ztchCusQL2WMmt_u0dhL0FmcwWVs2gr_sTZI8Ogx5.wAaebgeUxq.oYFWXSQo7hsZ18wqy0o_cgjoBzy9uSMMW2JLwQpcxVNQNOLSP1VnO9jOGD_XmKMNqfmFg86QJp4QvjF1yzIODP3v76.vEzzjRTTnFtw1IbEkCCkQA13945Z4Y4QxrSTSTNWLOz.wQn1oBcfOxaPt3e.ZHq3vlaoe.0ehw6VEp0g2IxOQWA8wDHiucg8VshlnnxcuZrznEoLYdc__mFjY4bM1I1qijyNO_sy6mYXYswpSknUKT3FPflrAYdUe6jZbKUW3gE_7MR1fSx_.L2OBn73FSxTATT7pd6OHk01oLbHhwL.KiKM9CmzoBR8aaoiQF_A9S_m0SEenOHCwUI0Vh0uyRqYIKEU0y99FoXJAkR5aBpcdre9ynSddH9fYF2DVqBPsGqWLi3jE.FPb1ozoZk.bfAAv60nKFgNCgldq.G7QW_GNPYJz3Xy9r.EmzgRQjxUYNca7FAH1gtWy.UsOLwMxhIbskV5FF0hpZQVajbwlycJlE1NtHNZFpXvlkddyNIqK42GMcZhjsKQMEPkLwyKVADBR9sATMHlTZibM._tl_ooSWHxUuPeZFQCVjDEFvdaeYvxRSjGJL40aq4JnbRPDcxHDlhAyngizf7CdW8MwCF6LoFsx4GPVmjTimoEyVYNXwR.yblS6mNU6VnXl4jHw"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/g/orchestrate/chl_page/v1?ray=92d96daecbe09b93';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, "\/1417.68142?__cf_chl_rt_tk=xk9wLt3E70UBedUwlvpfAMqqTl7ZrTizwiJQ_pJpif4-1744195668-1.0.1.1-euGn0wFU01omqVQ0FpBqJ8Y6cj5gasEyNK3n6SYwQyI" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>