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: '92d68111eec1ce81',cH: 'b1NazzyXKifTtS0v39.EJetx4IGUhH5nho0uauxc7PQ-1744165005-1.2.1.1-Dc8Rt9pLVVB5lJrYqwI47krngtTRfwl1BgqPJpH_cVqMi6wRI0vuzZXjZyz7As_f',cUPMDTk: "\/1145.82021?__cf_chl_tk=B2br5nRYWfU5KtAeKY5IOS65TE..UybrudRbGvkzRg4-1744165005-1.0.1.1-TShflDIRDircXoOVh68McIxdC5_wgforAxZFJRHni9c",cFPWv: 'g',cITimeS: '1744165005',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/1145.82021?__cf_chl_f_tk=B2br5nRYWfU5KtAeKY5IOS65TE..UybrudRbGvkzRg4-1744165005-1.0.1.1-TShflDIRDircXoOVh68McIxdC5_wgforAxZFJRHni9c",md: "EA0vIGKgSIDA9wz2ZTFoKbyuyxA6zT4YfQYYWr.FWSA-1744165005-1.2.1.1-mkHXJQN93cKqeJEO.rBIGwva_voBLmo6YkiGTOe6mdY5EtweWSAZu6SvHEfrVjYU.CNRfZ7i.zGver7LOTcwjwGeWV1u1.UoKxDOZx33Hp.uN8AeyXuF1HPhu_7RtrL9MhLSVq0B4FdDRO5lznLrUXh_z0w56nvpD7Z8KaavKHpqBPP8UmKfPvb23c85ZDneBV1w9thZ7G2r6CtBv9WF_dezzWPMp9lpSbn7q6k1WcXDCyZkr5e3ZlWJQMip9UHWccTlriuyP53HwbURPdKemf_xtg84bpRHTFuOje6vtE1mVnloF6RtQQeCT4PfzaYo0dmhnG8NmGbIkWjlU_HH9OlAaDiFRn5nqrgr7mPke0zMnb.HE3.l7yu8R7tu1yDwq3B32.KiHo3sBl9gp_hZdHc_CtCKqtiNV4sJfBchQmNmRJ50RbllH_4Z1o62WmIXe_TW5YhTBna7LQR8IWgEwcikLGICK8mlqu0xqG3nr16dia1aU3_IZJoCIU.4_FNFL_xXiWpQJfWZSybjtZ_rtKYv3D16kLI2pTlWCM1b2fE7QHcNoi0bWWKteOj4ZmN.MQGIDUgBoW7wOPHZ.jXAQXTkX8LVnGNcTuCOWu3b0nhbWwdlNp4Xoe0QiustBuPZbjk.kK_82fgsKfOCqde00lZUxCjtL6I8qakNvHw0mZY91nPomI_jfcAo9sbVrpgJK_ZgL3mLvcSZl70yHykCaKZR7zTMNXk99VrxJMMUcDk6x6CYz7jepRTrxZX.fFiw9qlbbu_prEtQHM_OZqk5C77IFffXwJSWhZW4Z.sgu_CSjYImMxgBjgCa6vn3.FKm67T94EmDbhJu6tOb9C4.XfRWWrKISJHJXM2ENxqCtBQJ0DGjnyzCLLtKB8krjxfgK7ECmMUiHa0QS7WjrmfpNw7OWytSBsbqLlHx3gXkCEY0MZmhGo5x4jZz0VX4s_tW1Y9SWKuCfNn2mfhnABCHxdxAX54yAXx3cRlE5N0WV9wZSCZZKzjhSmqpZ_ZgOPIaCIwst9phtXrn7y9dkXdm4z3seOMqnIENBZ6Qoc7An09sLl1rWUPA9VIA8.8tczT1uPdxC9K4euy.fIJVlwFm_5Q81wElEafABmIv6UienZlhpRKWFIbjOQLEUVggR098Y.aiT1wo0Q7d81r_xYoRtAUkuoTVbw9T4ld2sCg.VevS6bQHAP.WWJvM09sMFj8M",mdrd: "EaouEpBNFuWN...v2RbSLmEiic5COHe8Ga5PnqMkNoI-1744165005-1.2.1.1-hKbnE8Qa601nR_way7zJTQ0gd72h_E.07OG._OIRknkBFOS65ww7UlzxpYgGA_cP12X69c4_IkGqgbTf2kM7WF.haIRfpaeqUcnB6NBKH1YfPTPhPwCaxurSvAmp2L88NMA9D8PzSsq0xNoESJU0QHskkYkdjHqtg5HdIU1w9UfKEJUz0TipEnv1FO9IqBxvkrRIGYpcnot7LIwXmx.p6qjGd5aBAq1HiLdBGI17FS5gskrNvJfsBON2PRDgRr.4C4QQxq1.E6SAKCAZFS25XV6gZh22mzAdvYAIQCYKQaChjopDbIe0SHzq87RDHiaF40yS7dJCwcOgTJ.HouS0UokY4EFklj1te1U8miiL5OOKQ.iMucY.zWwhDS4tjheAiLAzr0OX1pA7o8uZl5gyf3wjZj5nBm4e.i5hbSaMHRSqeHKLUsRgw5a9zFbkYC3eZUOSjucYfy6dirZTE1oqOskpKwTc0izd1fVigZ4RncCTTB7kC7fhPBRuod3ot9Sg3am6_fox8hRNoaJS4KeVYw4u4xwomxJUMVYFcuw1oCEzEBeZK1LzFJp6KM.2qPfoYkK_cbo1cDLLjGSVXc3jtae1p4kHNj6GOIvU3mo3J1KJALhA3kZI6FFbZgvPlEBbJSdc3BogqOyeO6shtUjBg9ZJiE7IzRXATvnAICcBvoA05P89efrGto6CfznohXNrJGsn4JYhOeEitps1K_t1kBwIbWRHJ0AncRsH0qjmJPYczc8QwvBZ3dTsPHt5M1ElHTO_C7oF5TLh6NcpLYc91rZk6jyw5EgaFpHaJYqyqCdXTDntolLfsgnRdNjAvbWm8niTyuIFCsN3xppqkMOfPSi7rR5Bdrr7sCPADErtnopXp4KeUm1ZScdQJD_.0.Yrgg13AJgn4ahQp8QtplvxNToeFfL_U_vmPgLSiOqW_PFkSsjNwzgeRMq89g19zdzY4uJQWYhSiuY6tH9exmGcEwsIUtdh8iAlJT_0saXQaS8kdbx13yI5qP13lpMybXSQd9EMOjgPZ4QVKE5j8lktrCChI1BtGEcx6Im7DgZqZKw3sheqYjEqsw6E_hr1ySPehBvOQveS_4se8IbfG5R1lHsevRDaknEju0o6L0uYmcBJRJWLl39NXYmkNiqnaJj4UKn_lPVU3MmlvAYuxxc8mXpEZs09zseVWkmFUcknSJ00UbiNeCexK_XuQpUg9LdbE61Pg7oQEOJ44UQlvObUKgh5EQXNs_9KHCYkjWXxDbw2W.em73Fugb7J_UqJt6mR48NNetes0PjLL8B._Y4K5WN21FC48H_50f4alDKL7kgqrkrk39wd1Dcp1Vcc_Is82cr4tR8Np4A.YXI68WyLS43uTMQUbb.anh9.1Z3QfbbuicVAGW1Cp2vZswZwMj5izN4W.XSUH4Z3gfIsLJDvsnU4JmfpiPskjrQ0lYWdE0zrNp8yYw3fd_gc2xcUP_PWrgetYAdOo3pf2DEvquob_oPhs5AQBj4klIGEY4yIlsgedCo4l.CzZ945lUKyd2n1ypWlMNock_kKavllDBpxLTccQgFjMJKMeNru1MP5RSUbqjQEHWgPc.mddUps6GIvUW1kSDNDWC0yERs6XxSfPYyrliPA2kVmy7EjgmmBcYwjvBzQs50szQZlkgrgaEI8_V5ZMYgNoC0LVMmxtrMWLM.BSKjIMYz5ait8iymviP.0m0GPTYqyh7Sxtw13qXkGx62gBQTr.nu5vC1WIVliEVpgDg_oiNb33h09uzS6Kw2XH2N373EAQF5.5CW9DmdPsxhjlNKND4AKkKLecumbTBlezTDug2uNN2BBg7TMWAQ_V9vuiC6sYc.ZOX.ONKT9laVBH2PHPqUiZ.IcXxh5CxM8pfkvWj2zKG.LXROtMnIga16RTP8cb2lMWSxPgTft.EKFHRXIfBM7edS2dc_ewxTQTy6w_8binG9yH76nMqbJMCnHxvufMbguki6E8k3GDL0MtgjKGn64SpewgLfa96x7kNDQat7CVBw8hgvWIL9NF.h9ZSmdSvQ.6W__CDkk"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/g/orchestrate/chl_page/v1?ray=92d68111eec1ce81';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, "\/1145.82021?__cf_chl_rt_tk=B2br5nRYWfU5KtAeKY5IOS65TE..UybrudRbGvkzRg4-1744165005-1.0.1.1-TShflDIRDircXoOVh68McIxdC5_wgforAxZFJRHni9c" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>