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,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHdpZHRoPSIzMiIgaGVpZ2h0PSIzMiIgZmlsbD0ibm9uZSI+PHBhdGggZmlsbD0iI0IyMEYwMyIgZD0iTTE2IDNhMTMgMTMgMCAxIDAgMTMgMTNBMTMuMDE1IDEzLjAxNSAwIDAgMCAxNiAzbTAgMjRhMTEgMTEgMCAxIDEgMTEtMTEgMTEuMDEgMTEuMDEgMCAwIDEtMTEgMTEiLz48cGF0aCBmaWxsPSIjQjIwRjAzIiBkPSJNMTcuMDM4IDE4LjYxNUgxNC44N0wxNC41NjMgOS41aDIuNzgzem0tMS4wODQgMS40MjdxLjY2IDAgMS4wNTcuMzg4LjQwNy4zODkuNDA3Ljk5NCAwIC41OTYtLjQwNy45ODQtLjM5Ny4zOS0xLjA1Ny4zODktLjY1IDAtMS4wNTYtLjM4OS0uMzk4LS4zODktLjM5OC0uOTg0IDAtLjU5Ny4zOTgtLjk4NS40MDYtLjM5NyAxLjA1Ni0uMzk3Ii8+PC9zdmc+);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: '92d65f86bb95f8da',cH: 'o174IqB2nooUS5TCdNWqWQATOs6Sp2gmemjgbBm61hQ-1744163631-1.2.1.1-lT6VoC3R0i5xGJI9Zy7IvPXQM35ymxu3GXfLDq0uo8oZvVwChdwYrwDA9JMTLDcT',cUPMDTk: "\/0719.35044?__cf_chl_tk=.0LpOQhnVr3UZXGxhzkP_exebp0hGkoUMgSHZ9I1v.c-1744163631-1.0.1.1-bU.zvOMFIL0jM.S7qVZq94LWrpFWBwnCSOrwHRdi5.s",cFPWv: 'g',cITimeS: '1744163631',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/0719.35044?__cf_chl_f_tk=.0LpOQhnVr3UZXGxhzkP_exebp0hGkoUMgSHZ9I1v.c-1744163631-1.0.1.1-bU.zvOMFIL0jM.S7qVZq94LWrpFWBwnCSOrwHRdi5.s",md: "bLR47MbBsGe4l.9GRb5duS_n9yzeuv2iINgaIfWUSHI-1744163631-1.2.1.1-kbfBYCpAMRJMOUdDaSqxMSFfnRD8aW3n1.l2J9DRdrz65KgX37HtnuvzYneCMTF_AY.k6ZTT41uTZeVMgzmYh6pvUsFBg04xtiHWpLQ59igMtSArj245eiF0l5VwgD8v9N7CrgQnbgOWFDCisE8xe8cVZf1YuRU4GS9WQWLtuw2TQRwwnKBO76CRcAVmjPAU7yTwEMtalinqHg1GYrcoA.BVKyI1PlfytaNEmS9eLO7HP6psIsV4P9RvlM6YIcl7MqSMlP0ZHnkZsgPtyUL42Ihq9rZVsDOCsbQJvJYapaALjwkqJYpL.niq8_bsDMIxzpxsfYbNjLwyv_Qg2ltFmperXKCjV8_ObCaicp25.VzVDayeGc9M_i3rsNdZlw6U9JlY1L1_DA4PwQ1kY8tTvqTnIsV7nDYlW67KHIrUlLLhR6WX.0Drisnt92upgs0YJWgR95zP2eo5sLjhk8CH84am9yiq4cDM00YrryM3rYWBSsY3Rnco9hqJjkzJUI9tQk_3nqwzr7aRIi.BkQjMQ1GcJeGQV0HO8IGE1ZdlR47j9VfQbJjImgarBQDyhQCtt9frtUorRItBqxPcX.ZJE1xvGfb0CB5X9IcWMDzC.mH9k.WEPAcCN5987d_e8XGjQe0UIHtf2VKOREEAWVpaM7mBAYUjIIpdWP..kkSjTJWPM6MGdikjluKNEQOij6t8wGe91ekIRSjs0RIwLPVTjO3Sb9DSZz4it1cw_jRLQejwc6dms5Ic2ZKO2aE5Lcvjp9b.1r5IplKaT5nSFAhS_vMn3UDfe.m0VzHX9wq0muQl8fNksS7kmNhOtM58Zt3unB_XaI.EUgM48u_0KU37Gi_Ej62yE7SamT8qRCj9oAq7RdqitVxgvv3BSX7AuUn.4HIjdXoVKCQZd8gfj_NHkz68fdyKyTNszudpinjNyElMBIG6Y_IauG.FiNFcfDj2twyg4NQeChFwp_OL15x.vTkZ2j9cukXFcfPX4pomDNn3wmVEFDTZu73WlvueVC97_AEadzKGSX8CkAuDAv_cBRkfSKLu0GA26qECuHVAhTQ3CC_0JhX_bjc9Xu1g0QRn.eNLjKnn16ZF0Dhq.15aHD6XWsQ3lWL1W6JYBY1Q7ZO.p5mXn272Z0.ig6btH6beQmVZtgauh2eRtcfnekaOILBJ_jYPMPeCQ_pHzyY_HY2Nbbc8sMDmThdjQRDzolND",mdrd: "HXpETJRN7IRaaQmpI17EQS08WmGYZLh3oY8Mcdn_9Hg-1744163631-1.2.1.1-Psi3c5YPKZPO6z8pIoHFOVOfPusa457zv_i3FAZbba8Lzv06Vjoefpx2cTQmfg0HDm8ZD3jv7P2x5Agv6y3sI00OqHFkD8YaimvYGmhUhMRMMD0GfCl4.JKy1lT3.Jv2YNUsXT6K4b.d08hGN6jjo3S46U1BDJ_R59BfCixxwssT9AlpOxFFCCN886cIfQfDRqVLLarIgg2swYWlp01mCzRByZlJhxl0kHNn11uptULUBtwPJ2dnrKU1_LWdi0wfXXY4Re7HwU0H.jZnRjmW9txdweoUmX_aeE_D8i7nTsEZRRM9FsRdnf28wqlPTGhTDvpsKyumCXQn17jkw5iTaHIP95b1x1Y6RXBPdeCciJfcNfZp_nIcCOKfUfmK4KYJlx86pX5qTv6bhc_Z2tEyxbBYDkq9dBIUgv.tYuV6OV4s_yRa8gkXiTMRgQUXFbBISLmqkbEJoPabZqqVvkn.8aKEANy68K_RV9NL5oqWusvyrV97hQCoZlTNFvU.ps5nGNFFKjhaGkCEv2oJpZ9EFVpbf.N.i70yOIbesG8xt3vgPZD0cjs0p9zDnTTJy6pRKVO7XRig674SCqdP4WTOhbxkrNF.S0eIASlczLdo095zNYTrJdEBiicrWJSPGQPpC3Cht1mvkhdPGkH1rd550Z8UlbnCpjxu4pbvZ3y6alcfvpXn9l.yWVD1T6Xl8_qKgRrXZavf6FL4ukk6.RWT29hHzYCwxFHdPMBHRjZsB_A2oi3q8yzBN2.kA5yvH317f7.jiP1ITBnkCc14ehO2WGGhO5AZT9Jz4ArdijLIHvszTH0bbYfprR_dal.yIrq9VsH3jo03OgjGiZEhERZmUbgApfKuujz5nKtSfaiAomlUSANgY6AOJCLI0gNuGoYReJ8i_S2aOVy2MNhjhpMMA7CKJWhXftxtmb7otX06Crs.enqnkqtwcqvroyW9c3xxzLllmdqUKv0kJQ1gQ8ZD4RVC6asJFj3lNpAUTuZUlQwNW_LT80kVqeGf39.DSHFQkSMmooxAB7JtDQqo4b0WfUQ815z1M2e7G7.UJjJdXwl_MmV0S4yWSjXMtpxInPfGGBkaVazP9LEHVJBh3oRV8JwSGMGNYerlUMiZkVfXkNjaBQZS1ZrYD6LFP1uEKaeNyzARIy8P9LLwmvAaFufjK6CTjY53hMerNLb.Zu9L5dHmWPE0uTVjYbVlAZtIeNX24VDpFGQP.VIevt0BTW4wvzj35S.Vi6pcuU4B3GZ80KOCnsu9vyNy.G9q5WycMRsuqdvUfclkb9hNOqlm2ATlEoylNpD50ah1BFLGdVYWohNRieWFQWLoqjudh7TWwhInOV9Z.XVTPtKRd6_SelB3Lk2CZVR_Bm6yMoXrJ88Z1sGvzsITUW_QJgJk75tYH6okP34w7jCqZMERZWyzFvmQDyw9Qa5Ij0_NhOO8UFjmtDgZ3xWQ6vF1S6pbQbxQnV8.WgTMw6v1b_ekYitsAig10PHBSFVqq8loMxkG8t5lxEFnm_IzXvOAu2B7vIoZ9i89I8lwp8PTj0OD71TWfv6_AlXbE04MUanuJCzksP2m4RMOubxAZiTB0JfKVPLc1Kf7qqUAITr0wPHPHvdwS6y7jUAWnBELaV2jLfgBQpX1sMEFAt0iVusjIFKL.gVsw.tkIDayxczHkwuVedS4ZGiyyo45Xrt2xKGzoU52Tr_2XxQhMFIBaAc7eyX3SrnqEqtHnpK66OGi6beS9oEYmAFWlAIuOdgpRenRs2.Y3DQRlYuzt9JRBgj89gYYw35_xbe9NVSP2szxOUkHs.RZoUaXZkAMXVh5eMcBXsjPsOhJtdDIJiqDQFtawmCKjXCZIFRfoQnqrb.LQUynAG2Uav1xOXQR4DTwha5reg4aQT3qg5zQi9xrf9_BOWmnrnX46fjsqDup2qK1BU7441pD0248pJx1pneX8FiLU5rczwJGDS0jjoAFjdDibzaxHMhG6L6s6t.COkMm7tucpwUc0Kx6A0Q4GFbGGU3n60Mp4WiKpUY_0ysabV4SVISOON7pa2qd"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/g/orchestrate/chl_page/v1?ray=92d65f86bb95f8da';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, "\/0719.35044?__cf_chl_rt_tk=.0LpOQhnVr3UZXGxhzkP_exebp0hGkoUMgSHZ9I1v.c-1744163631-1.0.1.1-bU.zvOMFIL0jM.S7qVZq94LWrpFWBwnCSOrwHRdi5.s" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>