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: '92d45063ddc58195',cH: 'nZ1GMF01H_Lx9yToqIbTBe0__Ek7yy7biFwKswwSUGQ-1744142039-1.2.1.1-j8hbv5bQGQ8fA2p2vjGM2tpe9huVvVKPCQvwOzKga4fYCLBS.rxfon95V3aTTidG',cUPMDTk: "\/1143.05052?__cf_chl_tk=uFzaBuyNdEWiVFK2vzEbM4N8KbM.6UzZqPl1kjaJzvU-1744142039-1.0.1.1-n7U8nejfwgkYp126oVlatHczFf7_3_KAV1aN__1lzWk",cFPWv: 'g',cITimeS: '1744142039',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/1143.05052?__cf_chl_f_tk=uFzaBuyNdEWiVFK2vzEbM4N8KbM.6UzZqPl1kjaJzvU-1744142039-1.0.1.1-n7U8nejfwgkYp126oVlatHczFf7_3_KAV1aN__1lzWk",md: "sdJPwwYAbXdLgorV1FOX6khvncTLTjkUcVzwerZ7B_I-1744142039-1.2.1.1-JVCWQ0zvZa4mY3SV4u0lWdurovApE5g7K6Aqy5YgqANW_XnGwyQinjcCcWrsZC3IZ3jmNFaoW8WXR5SuDlNl6Zh7qHoiIUNHX8itYxuuvgf_No1z1WR8xNKb2DCbQ4eo2vfdTB3no03dpTd5oPz.Pdp_3vsnLAI5QHxYwFjLZCn5q7dRPwVrOlVmKLwHldv5btXHzPIdaDeAdwe3b5jQAQbZnqnbkQjxdWretnPKbiCy0fbulTFugA9AgaYHPZtJAiEreHLFaBNd..g6w417EmzfdYUYUfRQw6jY.KSdauiaq653ynHSB8meJNsq0VPt54f0QxM2eRk3ZTmHfwFOxJUb__bgN_OGP9iWZP8T1tgSBTfJkhoMrJYnP0XflCRcSI8DcfnQLqP4RNNDXE2a.y4dDAiG6_z440wKlcy2CVZJu747gAwd7xyk.L.0i48xxy3JIOxd_0RjiHkppBypkl12JLS3KAFZWmQ.T5JFwmKl9s.VHaqfd0__HZ.7LNGQA_bM9Yc.7ngcdKz4tI1Y_J6xFthYbUn_rXSpyHU._vZyJUtwSaQ6lbTlvrLXPTMqfifzPk_Gk0GmJmddW3CKD258t6dt_3VpLSVnwdMV9d7pwSi5cVVrm_PNyt3TD4Pny__ZNO0_sn48bRkTF5uJTJ2O.F7MFi56_4AHeJf6l9pBr7YUeYKtzCqOD9jRzPIFIRpTHeambmdXPH_QikJKVNuIE2ir2RTlBmIuzZEx0iC4aSvSx6X0Yy7T8fcu_M59QfGMQln36BYAklfI8nfEziuUhsPZtigMFS6b5.pnYDBnNl5NLwCEzoiArxKxn3ax5n0XgMFlkPvtjuTmAh5cOszFP3U7D6PdWpwvCKnHoHUAnp32e51vv9gJPOyqLojeGJxr0.40nAiW7FmVik3DEw0FA4PMV_H9CHiZr58rSqOyB00XnA.nRbq58GCXESHe6lHnma4x0crzoWYKsl0S8jhPqeAZIDZoc3.uAnixN5z0T8zJPztsAz0dM4LvL1bpZD6njeF3NaVrGgMe_dYwNbc62TBXFchpJ8gnS_kHhDWkW5xTEiDprfQU3pIgZKrgo5ED6KCMH.8AGDajjMv.RuZEXWKn623mcb4roFbrqtrDm.uwcqkHJJy91r1505mLqt95xUeyXVnTs7VKFq_Oux2tgc.Uw3QgoE9FNdc2csfA3BAfH5polc0shNy1RMfL",mdrd: "dP.4yGBFeRCCJ63EJx4ukO1UIDMNhXtOOv8l8gtG.pk-1744142039-1.2.1.1-yWBuiaGdNJlxzvBtX_j7LNIfDX5Tyfnk4CF.A.GQHQPGfGrQyBJMMZvKbe4JeQ4hXhIyWajjUVkBxzub0d3RyZ_Ua2f2HvfSdQaO8xyc.KUZWlTk1FVo9ysHqDRntq97qsV7iD5GsxSxW4F0NsufV8nCulifWopJTICPAthqppjGtrdCEJBGni30VcCaKh1bchvDsyif_lXILby8GftdgsPOs2kUbeDdU_Tygy2hC.IYHdorKevGs81nn54McL8gScUCPyzJn7BiCLvnCWMdiE8VogdtzVuqRqaB_uziHEYpWCNM94N4gYJJfyEQoWiueiFk6Eo.TkNL2IGQYz3ykpf3DQUayColbPf.uQcq2_3eqGkm0_YbKgflTPUMZwRzw6.zR9zs4EWKs6y5IlHz5.tvoQ1UbkhbBOg0WueA8rCjjGW.8EYYkIlxtxOj1ZZDGNJype4FdKf1qdPv5c2Ml_ZfgVq3KPyCsI0rw7k8n3CCrn.dguILWM_V4g9wFKtVzAq1_E0qoR_mpu5iECxbmEgo68OIuQgNg4xTqgticQ.wXeeYr7QuDa3xTj14CygcNM9lwa0YSnMZZuXbeDK2NZ_qvAN2phu1urJQjLg0oGZukXTIczigv1.NsZS8gaT8uj_KbMPvFH8WqrYabBSrvrdMOcZuzK.3M4eJ45y_wy2BwSwSuz32QfcqYOntf4wCVjZnMilyn.kBXKTZHa.hpAo6mCj6EK0qcBN2syhEkz7CgvmxExNpJ5yfgrMOM8DnWCrwUNQPq4qgG6nfr.iW4yPrI.2t.NfTLxkdetjkKkBswcrH_okmuPfny9fpYsT5fL8ucD8o_Oz4Y9npvM2CXl8oxUTJBLk6zoFHu4h3DUx2DOSc5XsiBp_S8xlQX8SHGuDnamIS0H1EEqJRxBF4ERXfuL6kFTbNiYft_ZYTe4oMVU0vUc6AOlj6H9n_sEGi9zWQwxJXrZ4KJyfEEwqe0TF07c5KyE494o.rT4A8YW1.uj2X6aDP_FUokNc2LrfykUgEF7pWqPhvlQ15gu3TjtI8SNsbBaPmHtUcSSe4PCID0udFQX16YwFppyle9xVw._Ztf_lwPJWuRWAiQllwvX.OLQvLpIiyI5A0tnhkuiy3uPWKaNBd2XMVIakJXxg6bPP8pxkeuJnWWjrubxGkv.rAIb7h440Wl_nO_xAZeNBoe2GDQaZlCbN6DfNwjtWcw5NLE8B1_XhtuxPlfXeRg6j4rvcvDJ2zIcnUZoS7rJVFIMamXQvF0NzdtQATyEFv54v6bonys8ivFHFecuk.f0eiZMDHuFpEDfUZmEVtelhP.4KmxvSPR22SSaQULBnxAbjVCtc_laMRIgK1IEiDfLfH0ObkKDB2eHDk5mEhlLww25m4.9EOfzbuwu8sUxZNLo1Y8v37x3qzgwEVjBH9uQp9rnxoyXGLxeGx1uUBH_RTvmrEy2.qJcXQfGBpdQ.MYuaWxsSxZnMRwEV.0_1vZ9xqxpaV1lhT8QJ5S9IatTwO9VJrneE6ZzbP9HvAQulhtLDHsj.UGvRo7DCq3zQZXW1KAL_gPtnvpaDIjATQf3O2FUeUAHyro4cIVVlEoKpHEwcFyDMnDbzosKpheOFf4Y.Ewlc9FX28b5jzcIcOr2Okz9BebBwwFKQ7Y_ystO2NpVc8ScJW2JhB0WTEiDId1LZ0T3k3GzReC5CYhHTX_MaPHDhqDJy4xN.q1AAXhnvWP4JgyYTN687Fw_Lfa_IEVGvAe.NfY6jMxW39fWvm2HlduThW7HR5etxcMGx__XT9ET_vWYZzUcQMjVQymUAE25be5Rau.G499yX.Etb_obI_9v53166.sDcul9f13c0vzLGcN5N87MIKtDrVVVZHb_QottvDKIqa2q4fenm1A1_oEjfSyn.ixxF0EG_Qs1WkQ93CS9CIH7ntOgNh6CLZNeqKCKHvDAKudDldcfk78eM7fihVliP_xjXJAQEp3RdGTj76WymFB2IxqGTvqqVMiLoaI11h4js7joOf_hqyzSq2G7P._qdFci0_E7ywByHU"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/g/orchestrate/chl_page/v1?ray=92d45063ddc58195';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, "\/1143.05052?__cf_chl_rt_tk=uFzaBuyNdEWiVFK2vzEbM4N8KbM.6UzZqPl1kjaJzvU-1744142039-1.0.1.1-n7U8nejfwgkYp126oVlatHczFf7_3_KAV1aN__1lzWk" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>