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: '92e4a659397e3dc9',cH: 'zPmlTQ_4utpapOaWbQf88Dc4.iu3OVY.a6wNvk7cPls-1744313332-1.2.1.1-N4mdFKbat1DzFo98in8CFilB3RsBDkYZN1xFFjqfyfNDClCV0wSpS67Irnx5nbg9',cUPMDTk: "\/0571.90090?__cf_chl_tk=Jgz_0kYacQK7ZDYKdUkjm9PUUu0ztgXeO9rBU7q56DU-1744313332-1.0.1.1-8DH.YAXvJsyYBWFMYxOqJ5BPd3CBJxnwRJzN50g7J.U",cFPWv: 'b',cITimeS: '1744313332',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/0571.90090?__cf_chl_f_tk=Jgz_0kYacQK7ZDYKdUkjm9PUUu0ztgXeO9rBU7q56DU-1744313332-1.0.1.1-8DH.YAXvJsyYBWFMYxOqJ5BPd3CBJxnwRJzN50g7J.U",md: "n.jwaQrz_rk0hiRG56dSQ3FmeaI4eS3IcZpqOCJyLc4-1744313332-1.2.1.1-OqD3N_HNfzgmYZdf9YH1nkK2OOnDJE9XBa02_DT_bD0sYYVppd3Rqd1Yx8yVaT09Y31KcDAc9dlx27jifthQwZMCbpD94PUJGyGbNZigj1y7a4lf_KswjF6RYgTv4XfZ0p0xube08wkFgaA3tV4MGm9L.TdpZw4JibbGP2GEvw7aGZbPL5VlAc.10y1rIqIaKLo01dprJbXaWkpYe5Q7ZYfKQwSGRqlbdDyTVMaIgcaDGZvFMWyadNbREKP5O4EC9pLtAMBaX..GzZ5D14KTkhNXc5j3RRSivP.jrthfs68e7UltKjCRTBb3vAF3bgP8mZT4_z7oHTL3XXVf2jvFXVcIolPju592kZ4c8BNVBfnmDke0Zo4ldL5cd40LBlj6gbv_waNMKfBHP4am1BXpIBI3ksQIom84ns5a5faJxirFoTld7YUg3Qr.csIf0FOpcrrMFpSY_wBg0oMtZJRamCuUX8jzoKqdpzq5PEAVGl8IB9oGwXMMDqoUIh3wBfzmGIjvD1ENs8rtrBNZ440aEOqUS5xjMbex8GOSE2kktbJp8Px8u4ItmOoW7DNvXGRJayi2qI1FK4MhUCWZTosSjjf5NgTjYydsm01q0SzcierBq5qEvgy1_jkK.Y7hga8j357OyqO8TrQb9Cq3F9_kWZMTHoWUGQgEfta.jdhqaePf4CYcda33_zAtj9tTn.NIBIs8YjIm.jIPKG1yWClnXMbEy0BfJwaHe3N7RWeTE6E0U5uzleD4iHML3b5q_ysaWauzdDKGkHSHXpFMiOyW21Xi4wqFjvWWNtd7vIN4fIJRJkXgix0M3CrDdbA8pkt0TcG88DpyM20Ueu7dMGXDyeOAcUY7xiFIIsQsIsBgLFZWMb7lCLj37Paelk.PJ_IBg_EqWCmqCROr7t60nKuhqL_ZD70BLcRuP6t5B__uDhEN50bz_3CWRqBmmdpmv9vQgr8iScZR5P60ib8yk86RhxclU_elQi5FM45G_2vPmYuw.ELnQAeydK6M.NnFjfQeah23UyFENmYifzPlDZM6q.9XTVQhkTICJNvFNI.VaJc8fkuOVs0BWY4dbDmDMH64ngm7kV9jmfz_MwPlMB2YWEe3JDO2ZboNYwwDx5dH68vT9vLD77iie7l2xbu8zixsAa6y0DTzLxNXkjzqqG0vPYuNtQ5rXJ0fCJbEkBQldakhi1Z3uvWinaHKp1qsaZsP",mdrd: "49oY3DeED3rx8hutxfB5WsKJhOPuWRHWj5lx_QeIKsE-1744313332-1.2.1.1-ZaBVEq3OSEU7od.4EJBkb8JOxdEdbSvCcBSzbwPo6YX093KdP4UbtmK2B1vEiwkO4b_McoA0eAafcyVKrjfi0PIJiETrbtfIxuxvegqTkJ3IMjSkPLW9ZJm6olJA5o_qh0.s8LlPNzzFcOl6A9Edl2HOUL5ZKyvbIHkc.j0KWkL8d91y4V73HngSEeh7nAMRQhFmQOSp_By2naY_aMhbAwAkZfnRoBh7Xk_pPgZCvBG7ccWhEfVyUmRwZ4ehRMV71GILjjzLUTyQJhpSSAnw0lvXvkAT4arSTmj.eJsOaZQ_0qRA8eHPgleq1iGDw3XpOYFekArsQuoTjN2EbyzzeovkfP7Ce0.jHxbQ_ecEWSo34xrPv43Ja6O48CN4Uf7PgvBbMqBqLqMb2D8nU1bODYP6Lc0cb4d2w7tJ6avGipTjlRWGCGvkpkrrEaSUCHw5a6vYkvPsDsIFmoomL7c4HoylSt4.7M_5IprZNkZ6AULZEeZexyCf5vJf6_0FzIWWmXLldkj9aDtYIncuTBAqGt1QuEGhPqIbmgGShhXFpqaHrjCXt5WUkW8nPFqNR4obaVtRneHUs8GgBRi7hMqweXRUxZ.xFDfXs0naKzRdMBlbnfaz0Q5BhB94GY4f7TpPP6DUK8fRvSMZU6KuorbQY0QRYbovEheBZhWOyJyLn9q_k7qqVa3cilQgx7Q3YQh4gth09BdDPobj8xynP5EewuraDe8ndJihwIh4qYlmeBFtbH8rXMGg1EAImdWvE6JQJHUrVgs3B7HO0_OOIIeEU4GGPmjfXkDHKgrqyBnt7eo1qxqLntAWiQiyq.LTIJwHcP9sXb_rWKbNb2Vx8cV4zCf8ByBnjr4huxCIqjBzDMFjTB0ZEZmTzb4A_H_M5YZ2wqZV92XKPAazOGpNjw3.e6oL3X_JucTnQavdY6R6CPTj_hrHEi0vgNGvaafIVEzXgXMMPgvyRKP68p0YbM.j73BCmCtCnOVE_aZWtXQa0tzMXkgTqP.Agn2AnU2Xa1mx2bii7bQGHZVqqPEWhVrIqTulpmuTD.baj2rBf2DgLdeXAHpgvs0.7DwqIy6d_OYyizi6PlThcsAhVgWrwr0yGQePeuQBpClxVpmm_LwBzoal1n.t1gtFo2IyF3sFoV_YEH8XzF6c94.OxyzqtsZifX8kW95e1PnxQqR3FvQfFGU75.r3pjB7hAlQWMYXIsi4lmK9GInimeu8PVcM9QcNPSEI4v0VUVWrXH4yJUbLfr4gqpgDfsxvwn5iopaE0XVWW34YOSV0b0vJ.gW7FRU9qY9qDshZZbhwhc2UqFPFzRpu4KY_ZKqVuQCkOcfq3wo9JMP8p_DKX9I6itQ1xhRDKamjDxJZiGPvm01pU2QIMNkSIkPisZ7LEtlMIRxyXKY3sBYWY0ij6aguP6sWmHgKSw_m1JoK1yRwF6lGtFAfubcRfWLPJSvUBkb5ED6.HYG7DmC2bHQlSvqNFfNasOGJw5Cjv9Ym1iTS34CGZnWPbKVG5_CNIs5BTc430GbtTsfZTnEKbsGQbDRqpK6E6Br9IxkCVMiQybeAO1VoMUcvlDTl3eFIaIWhFZdJnitoaENrw5nSqj6qwBfOybVlTAh12FgwYawftkL0W3pq7HnbS1CvWEdzkGZyC0LKlPG9m3IXWusjfRasfVmVtRw9iw6QYBLkDr11JE9Ih6YLpQRqRGoa3w_9PYJMUtcuSX7GMg_nx3z.YWvP.FAdg1ijDWv2dCsJlcxsLjAw9RDMm_gktszOb82e5cvE_Cr3d2ktREuoj7EsxWrFhZwwuPo7zqvuj8415R3e__JLa6qBkNfXaLV0lVCUnhkp1ZtSWHWso6EA32RzeYOmqAvS.tS8.Pt9LB8lWksJdVUImD2g7jXLD82guUOkdIbcXJIMqN0h4kCtSH4ijpffpvZhnNojiw9oL4ERuUaol8E.9SJf3yONjHiXzIibhUIeJBArTOhKCiI_8srfOj8r.1mVfS1qUnHyorF4T.mBBnQKp9AhaXhTJLNVXqF4wM43wkatOfrLSno_"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92e4a659397e3dc9';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, "\/0571.90090?__cf_chl_rt_tk=Jgz_0kYacQK7ZDYKdUkjm9PUUu0ztgXeO9rBU7q56DU-1744313332-1.0.1.1-8DH.YAXvJsyYBWFMYxOqJ5BPd3CBJxnwRJzN50g7J.U" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>