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: '92de5b6e0ffc1d47',cH: 'sNP6LkarGtuPsvXQ16UdFnQugoB3R9lFhFcIZZMWmns-1744247349-1.2.1.1-ORElu7POLdiRgNt.6gTwdev.m1CSAJ_Gs2nj2.Er_GTX_PP_aIVRPjzXo6qOWwY5',cUPMDTk: "\/0993.92033?__cf_chl_tk=avjlNXAUaUF8Ne_21yf0PlX1.DRzC0EdgTu.qfqY7Qc-1744247349-1.0.1.1-atmnNEzWzmyDJLQ7f4ekzuYv4SNw81ipLE9MnebaviE",cFPWv: 'b',cITimeS: '1744247349',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/0993.92033?__cf_chl_f_tk=avjlNXAUaUF8Ne_21yf0PlX1.DRzC0EdgTu.qfqY7Qc-1744247349-1.0.1.1-atmnNEzWzmyDJLQ7f4ekzuYv4SNw81ipLE9MnebaviE",md: "W4UcO1dnmW323tKuQvXbadxlEx9craDvSGp1F5Su5vc-1744247349-1.2.1.1-MLJ1G9oUgAXKk1xt6VMwr7II2iTlkKej89hvQ32GFqMeC8IA8Voq0gMyxJXMUS7Kn2V5nWLPul3WfRKLL2nOGZAXIL7s9mukrUqUO5yBo1MANj.LtayMNOX1phyP77pPLcKUK5DNDYo7vvZB5bd.SS2KxXt1JqkVCk0IKU9wMlZubdRWJIvn90JIKPhRWbXOsR3G1.xRSUms2Gp3XluvpwwQU0smkjav4FtRtO.Rn2kmluVWM2NpnOXEpb9alSdeR_HygBG68WF0qEvHd4g5Z80cXrqWZgHVnb06U3nMrfSWxGXZrKPDvt38EvYOUfVHVWrZLW.Zyy.8GONbCPNNWpZI5S8gCAaIWsZLCCap21yYLmRK6svmFQ4hC41GgvbL8CBhGNcm9HxyOeFxoXj29cEIr1VfimBPHq.UswMhaHKFyru_zN2nMIbcqEXhvJl08JRSKGFuNVn95Av8KUqWJp5OiZrJkgSQRrvFexn60SntkE5.a1aZ2kldBaXjmSwPv50BWCAM.LsmFkGVbiJf_DC.dY7CCeBLjuW9Xw73vgVvEkItEetdsh_xZx0WLkg4P3SwaQaP9ec7sQmNrjRwnDMKz32eBtBktBkJ_BHLeAjgVhqQXJZXkiHubAN9TfXF5zFv2vdzaTnpbGRyv7DuEDkGdGtpTJoRlL.rw3RzILwWF9cTqlI_I7TFFkmIEMoODX8J3Oc4dmUYV.FhF_yVF5Rb0IFaQ7INW.dh3JyYYe4D1ekmKjw2cljge96EasV5Q4ibQtiIhlNCw1NTUhYTru_juq55F7OnzcxNSweL5g1bywgZgGTh.0_XNUmlgEI1qvPs_1tmIxer1vtGtaw85T14uGnULCUxWHJHLfBtysBwoKwPO4nMwhO1nRvJOI.dPmW4rLOj3TGouklYY.Er9jYjjRBtsVZalJpV2WrCE.7USjs1kujs3ih2ET6kn6BUtMtMK4Q60LrWUu8JEqLi_RccJYiriSGXLtdFuStK7r3on5y.52n_66WzKbe8LCPn13rmoPlUadTHfBFrXDZiv8WgOUBsZ7kywbBwux5_3.fdRs2tXUq_KRbnDJX_EbdaTVd2.dw0ZjpOeQXwmMrW09dsd4U.u1lCDr4LWv9Y9Tl65KlsuIFNYnD8JNCQCta6rXM61NDegAfFarJHkV8YJUa_idBNHD7PadnD48vCLQGuaXTe6rkAoUPHNVBwUhgF",mdrd: "qDP4iI_ytZtluMRtzjcO7ShKxVj7ImVLGtjRthN1Se0-1744247349-1.2.1.1-3IxuO575O9ovvsrr__6DwinzR0eoowDtD3efi5YbgMjJShpMW2y8.MX1HtjKtYgdsTMdThCbs3hMTZSMlm8SjRqZIRqz6dkO1LvImTPC9lDEy2EzV0BZHL2QQV2XhCdusZnU.BZjzV3lsuwovxNUIttRYfFr6q6TDDK2wzajJ2vtC.h.CpmcBJ8UOjgZuz5f2NWpBwfboexBq9efDmURWiprlbzIaOGOymSxzcCkDtXWu93F6JN7C2rB4SAIici5gzrTt04sI.Neg4ljvXBnHVRmIUOUqwX8awuygg9DmPoDP7uDJFr_wgVNXu4lyGy0HqzwRCTffz9sJiDzb6ka4cVOI4qhij_VP5BDJnDtRO_4PNCpd3kZwKoRgjBSrzFjMch26uRrHOztZQyoK_9w6Hi1Ul9uUH9au5W7H0qVBpPvIbO08DK.1V.Zg2pjfvD0lqqfF.wMut1CBghP5s6y3tD5mnEJehnJpBrVDZL5hnUmFJuDOKA7BX4ywqDZYCrM3Lakq30nquD4SloGTflsKZg7vUpAfQPtT_dSoYeveNSvJu1AAaZMAb4psRuDb9aX7XCIRX8BgkUjaRFIVxo_V1SO1bwt4V.MDyv_tO8FmbbZRUGVRtQQJjh9ta48Il3.mQto30z9wiWZOJdzxRXCdKMrzNs8gcKoNSU7TLkglt5._8luVDsffLkQOHLROPHz_WKEKaJvojp36VcmdlpQ2XgkxYm9BLGTZmf6sFXunAHyNuuT3jTSdr7sp5OoAm4YVtRRWQoNGDmBxopVCP2W8R97NVh1csMYm62jT3Otqx6cgw_teQWsPK1kisH6ITD8RikT2o.hKhyxdPeDSoeYI_g2wgV.GS9.K_iRnbOC1bPp721YQ9id6Ja4qUh1qBNnwd4DW2sUVRq76gQ5sdDlqCx8Y5stPHIBKvcFxuFq63mzM1IQRt_BrFuhU8hWLrje4AR0VR8rzArthcdFUy0GMnaSo3kdrabRP542XjjNeiBKYlCI6uN8_OcxGOPmNAq5aZMQWXc8oVSiRKigm6AoAU0E2UQlkgAEiq.xmhRzETUuHbDG5lAkEkPYO4xfkEyr8cOLjuDojmEhkktUt1muXbOY6dNnPdsoHbsC.JC.MCylmdmAHRZXdrqBZGjBwiHUBUwUHitvJO7tp6XJ8Xhj49..eCuZYv27LU5Y7_ll7XKwl.ssobE.KLMLvh4kwAXMxXLYNUhgBH73Ow4824koB2bJwm4SBDG8LV428RuBK7WSiQWgslX3sp0qfqdxhSIcPR3OK3ohd_CpfbN4WT6jfBmhFpMIiM78vqC1JshlypcaUvk00MqPXBz5jCNlFaMVLeT5cOOU1J70GXjaBtQ3dtjt3g.H5yKApVy4fYZmZwGQh5cc0dgaPdfDR0RvYO7oH69wXDmTD05JRURd3hVJggOzeyBy37Aki.9Tup0LXKO53n1rAxQyKzDmw3gu5mNYtM5g_rxtuPWTfOicC8PKMj6.VnxZoj._h9FNaPA6KoFTg2NqzE9QA66rRbEo5X4sUxCZjZKltp42sbwkyLeHLK42.w_OQeWf6ReSE6jtvBOfSSpKtPGNoqkc6HEDmEgwuwjUz.q8MVGk_N9Ml4yYE34KuZVgD8ixMkjxdaovOdBc8LLXluCNSVEq3Q32I3jXA64VhVjSZgWj3.hmJb7hs.nBFcpqn9Q4Q25l_G0.ILI3S9XVbV3lOPt66roN0lDDgYpbxQXCNTaQ4Nna3.PW8b1_tRkjQipSVfrsezxMMdaR4YMM7NgvqidjjJGsQEFg4TAiZlAxaZY2R7WUzEt83uQZqQARCfE8DSa6LIXJoYQJB_DlnMSXHu29OH93j6niZjKRKMyeRXNUwhOoFcpeTfqfQW1e0IdnWTLqyZPQE00lGpWwQcj0FYLBL4lsriK9NPLX0RzHp9BooZ1OeAUSl7n9aSXgA2TiUWQ.mZF4blUsCaI.WUs0gQAzmRWx8I_QmLx8qZeFFkS1W0kng8tP4RWwsNUjE3731W2dffozbFtOsNzpXtE4I6.8LLDC_f8cdowVquGtsN3OiQ7H90CjMA"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92de5b6e0ffc1d47';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, "\/0993.92033?__cf_chl_rt_tk=avjlNXAUaUF8Ne_21yf0PlX1.DRzC0EdgTu.qfqY7Qc-1744247349-1.0.1.1-atmnNEzWzmyDJLQ7f4ekzuYv4SNw81ipLE9MnebaviE" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>