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: '92e51ad3eed2fe83',cH: '6pMbM8Fe9GL.FZLIUqJtUZVBhGE0eDsatE1Q.8sLcd4-1744318103-1.2.1.1-EWx4qvt.qfke6sH3wTqNss4cMozqkacj3xpfvzAXSciW4H7.rb6jIOX0f6_yGZ_T',cUPMDTk: "\/1406.35468?__cf_chl_tk=4QNyw2gF_il8LVfwxjhG.qI7e6akArxiLAvMOAjyHqY-1744318103-1.0.1.1-6PHZmfurkuIvL11yEqNQDtNLMzB5n4W17d3_piPuzs0",cFPWv: 'b',cITimeS: '1744318103',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/1406.35468?__cf_chl_f_tk=4QNyw2gF_il8LVfwxjhG.qI7e6akArxiLAvMOAjyHqY-1744318103-1.0.1.1-6PHZmfurkuIvL11yEqNQDtNLMzB5n4W17d3_piPuzs0",md: "klQgEm2RBKZHyspU9cj1MoTI0UMGp_C7.qXm7.ds7Xo-1744318103-1.2.1.1-18ftxvHZdFhRehMM1NJtwcwrJ.CgR.m09e_x_Jqxp7k7mVp4qFniq78vORb9ZDo9VPvCpSW.Qk..8_g5i3k1Hk7K9ZSkxuX2p2IPE.aoPp0it0bDorPlg_ury8hkEd_6pRTxa6AzQZ96wkE3Innu8RJXkakvbOjruw1n_QkuRyvKj0QVlW2uDQ6L3Yoftz3gfDzNvw2HxI6vgg6J4YrN.umfmicjWdA8jpF7uJY33q3urmKrdpCogk5.SAiZWrU1baVlDnQHo6VzWh9wsM0PV96UT.mdKd4_iKbQVdqH62nOoZre0DjUFTjh5SHduUHNrECq19yVDQMTjqJ88ue6pDGGC1dhrfd5Akqva1HFSrm07vWsh0H46XVHxZMEkEZFhVsGlGf.xnNvgRn2sbIO1aogvWMhxYAX_4Q0rpPD.02eTOe2_xLrn8lD8MU1luOK2DG51Q3ra4TOwLdF4R2.w.58qrbsScghA582Aeym9irG3Kt5fCpFIee8fG7gy99uf99LFQD2FlPw0udTYGPhZbhCeA5x3Z56L6qIiqWCLTZevqgSlMf2N.UJSKA9kYf.ddoIkYhTlCZAseIJfISyJPqdXXThCG65eiYuspzqy92fRpXB9U1caIKAct24yePRALJ7ULE8lBGCfMwzAwNPE_JkCu_ktCmwxAh_y3xZQBwSPaRpIB0ccZ580IYrRtWni7pQB5DphyK2w5vvEyt45BbwBQuMjWBYqExkcKixQ7huLSiHTXwuNFo6dVLyTtzdE5IXbnEM1gYnlKOiWF6QnBBVLw7MilluYQ9WsR9MKVkiMkyHfqiK.0_TDnhocwhSawLNyIdKpz5_l51F8hKO21mkiS5VHpUBiocYiI1KWds6puoPbdKdQKYB4WIBLOxauzOoDLK_cASr98huEHvJv0GjX5f6QvNNJ2CXfVVdwOhJF_MMZHpw9PSoIvm9vyC8on1QKEgMbni.yIxngojDRKlGrtXjXqudYY6.lpCTIJmh0ABPjOObEYlpqCf4c2tRPsBgG3Hy.mB4f0CPSi4NwTqP4RgCWVlyknem0o0.cLrMfv0Bkittn0u1x9jD_f8RQoTA0pSRAKaPX0.0He3a0Cq_qInxhAN0xQhruh0qcG.mlG7laZ7ssL4aoLUno0wL3_ZuaU7gvHMABSevtASUAnuVfbmlmBd.8Z4zgRr2nDx1299YT096el825eowUjRO",mdrd: "SBM_xmOqFigOx0zyuFORL5iPoD8Ui4thPQOSdddXvGw-1744318103-1.2.1.1-JkaHOIp6tvA3SO30eYJDvz9_BDvOuvJ6_D3MiYphuC2neZiBJl9fXhwdbFloylmzz.SWQOi7mrMQOa_J7hxjCj4VH8ZU0FqKFprZqJ8MxOoXhdnAUStkSN.Dz.HQRQRWDU0Gj1sq8hhwjeMqCzfhweQKlA4OG4OO4JttrXEL3jIfJa2hZbsVnfclX2NfV70kLK05xQP16g8fo6vQggmYfVUmTjz_ZoA5tG7KvmDsqq01530LUkfmx_o4kzbexOlCULimJaIwoX9R7wPPuYByE3Cv4JMyH7.pwOh.5ScdgZT3aYpSj0UbiNwmXJF4fb9eZd6ve5Bgk4Xz.IXee7xASeXwMhfaRHmM7A2VU9fqz32hJEolC6zKcRouoachOFPL6C3NgKLaPX8sWd0ELWhnSYzOLHkJkRb_R8ZzEKmjtM1FjBrq.9QefCz6Covm3Wj7hKQq1.ahg9kR50tr6X_4t7H2HEuIH478JCJycFO2_OF8ee3qNN4dB7ZEEoF9x197o4TK.7ohYRbbIjQJncK3vXxia0U_E4tajUiYdLevLvx4CQn.UzvGu0bfxKHZL9nhjmmKjYYBn.7vrWnl7nhrDmibZf03tVhFWdZ915MUZGivXeTBrq8USSGu2l4_83rDggGa..v4T3sY0lm49h5.rBv9IGPttx0W0RZC5vLUyKnaS.HSdZULYF6eZfnda5if8xxzXu1T2HIxcSpVoCX982.t6YgcEIGtDAr50qP8ZhKVDcX2cv_EAXa_59CnivXdWOGP3y7ZsAl9CqO5.gCTtuIVCSwsIDiG3tuRRi5JAYBXkhJlMATffGIO8Yprl59Q4VhMRq3dbe8QgTb3sZnc.ivVv_eqmO.kk4Asx2JsgTG73.wluc.mVzcLB.mb569Ov8_OJfy4gWV.Q3QwOhXpqN7efRPMdqMw4aSH_x1Y1hHbTfEyZxIl4uyX6VKUFPoNS827riZauldMuyToP8pZVlDnfm8Bs7hrt1._x5Bk3zFqvRnLKysQZdzuFp_jZIT.Xa.zd0a0ZuDsjB6LXsTaY.bTTZB7xZYsy_a8nEztoPOK8NjiybnYkuZQvJ_71QvQwEf4xI5UqtVhTs_AsiX1cRBmHuT_fa5Broo55dxsLqNsL.YwodqhqD.x0SQiaFyvicY9A_rx0h4y703EZMmDuIPfSn7GmwUxT.UOdfE8DCCgOCcUHXVgfriWZZ2yAR1UViDob9xzxF0bv5Bu6NwEYkj6iAlqIAPBBxSUe53IaIxjK8CqqYapX2E3qCtAQHJO7hhly10tvS9QsogCKV8AxU5hEPljbNN0GrR8.cAbLFyJQs72Iq.RKDUGtwvU4iohsWGxbjJIultXZAFcVCaDXpo3VOJYsa6erOpG26uxnNMP5RSa6H.kum4ANkTLvBHJJ4mC1UKJ4pEhzgnbzORpCfKAfKOF4g_hllggsPfBQjXPDXnze4cTpGdFCsH2GM2y65N4yty90y0I48crrWEO2FP1dQjsEm_J2E0qkuOflNoXc9W4v6eayI926Nvc2qMHBlPFHl3HAOAHe9MmZaGd3T4qJl9Ylidyng1qcJx.4BRrvJflMSj29B78xu7XLgJhCSp2GsD6zhcmN8XBiQmB6cNPd.D2v8y09ZtbdNQOm2PP_LrHNpRpg51OLogZL7kgD2rppLPtFl9nebtXDUGMEE6iT6azDBCAfcsk3KT1TaTmsIiMr3nOq5wVkwoepNRFMUAsNjEzN5unQ2gqtkFMBoQBx4I1cik7dSvwEw5iNAHpmyHxrYokFuggDLgZTl_BMakb8NaE35Nn5YbEiWH0DDz5u8irTnSP8Ky8FZuI0aUpEDQXezQS85K.AsQo4XAn9glS44gZAL9V3Yz8QmPK5IyVPTz7.wlfAMb2irrJ4.vi5wuvJZdd73wVFBB_1RJPBT.sTsqP.pFMvjm.kw0Wgi6s3YoapIGCFYPQVg7fSd7gowbQUNguQkLq0Zb5_I1f.ykrcLHYuFX6wJheJJ4OzRsCXpThorHGclVBzZ5fXVMC1bGl9yrqaHZ4nGbihgEkh3R_vhzwLDvZtELuP_P2Qw"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92e51ad3eed2fe83';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, "\/1406.35468?__cf_chl_rt_tk=4QNyw2gF_il8LVfwxjhG.qI7e6akArxiLAvMOAjyHqY-1744318103-1.0.1.1-6PHZmfurkuIvL11yEqNQDtNLMzB5n4W17d3_piPuzs0" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>