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: '92de7c832de4cdf5',cH: '0z4PFTijgrL84pTseaatr14vYEqS7KnB9gVKnaY7RPk-1744248704-1.2.1.1-ogBM_fv6NLHGWfSm2oEZZR8k9zEkUW8hsz_asfPUg5Almpir.S8TYShsX7_iY7X0',cUPMDTk: "\/?q=rf%3A7553588&__cf_chl_tk=q1NGiyttUzhptFjPLRYjCQr2q9nzDAPs2H2Szh0JkzI-1744248704-1.0.1.1-usAmN.nfvUr.hXd8Og7evlAR0T92IqGB7l1xiLBjiCw",cFPWv: 'b',cITimeS: '1744248704',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/?q=rf%3A7553588&__cf_chl_f_tk=q1NGiyttUzhptFjPLRYjCQr2q9nzDAPs2H2Szh0JkzI-1744248704-1.0.1.1-usAmN.nfvUr.hXd8Og7evlAR0T92IqGB7l1xiLBjiCw",md: "K3xKtwTuGaul4rZeDsz1ZCIIhUuKyNuSrIOuTGEVk_E-1744248704-1.2.1.1-Xenq3e8WikyvoH.C3wcRq64mUBFnjeQ..qjWTF1GeGs2Dk.ijQP0ATsb3UFgSMDtc.XzkYV2T9WILHMiarn82ryx3mFJRPUMAVFEqvgbnvEGBeSBDlMj7zioM4KXqLJyToWHbSkqjLSHMmVWfoJr24g_aVeMuQm62IsTEKT5X_DCbVosSRQ02uoA8C.rZ6AVdYaF3.tLDvN_MVJtNmPBa7Ss1OJAjuAtiQG2YeCgvImeu0Sc4ikDAtv83CFykfeXpm9PGrsMcgVPkQoz53OJbiGmR7Wvb9x0tYbhwXJOqObqK4z6g6NtsW81gdjrE.j.QV7GCeohaiFZ.9ssc4ry6yO5r.EMujWSTjyXecj7JACzHaVNpp_CmlQaiOBZlBnUluY3QMOwDonyuYmQtOIbj_S_Y.fjP8X6umTWTk8FiRPSjDenfkZDdf.c0WMtzfWyLczUv.TBW4ttWIR2HW4ruT_pE3UNAknd65WAbYvZucY5K4TmMAkBEBru_kZWK4Xd0wiPZc0t_qnNJh7ZWfO9GeGF3OZq1nR8capHEHQn2cMisJDntV6pVR0m79clpfN5GBziQaRu0SBALsO5JFmgZUfDBidQB89gmNxTm4vzxOH5rynUUnvkFzF7YwSUhEZUo15N01_T1xSLrYlBMQ89n3hYlFYG3rrxuzyoC36lq6X6qR4zm4C9GXDOGnpggWELDhyhtwtxHX67303hqyGJ5v2CMj8hRICntm4sZjg73_qbDLrECqMC8EFb8koqUuWXUFDuvcU4eF33zc6mL.Pr4C9wo1wuMv_MuSW1Bef4a0tOn6nVnn0Rdyv4iixgcFUwtt4SonxnJn6DTm7AglK5wsjg89T.xB8_KHjYk6c6OIE4EuT7AXlkJmUZhyhowXoYDF_QwLAfkITf064GfUmgDYupyN5DA3TP51qGB3mvOPv_RXYoRpE3gnq8OceWDV24R8jHa_EOMcEzPse2lpFBFXipbYUHvPrAeBibcJuHmzGTSl9psFjcWafXWIhh6qu5wQ5VaHOBtBxwsTsbF1iFeTJve1WCO3W19S.efdea3oJ6B6OhvsWdKwx6MCKqQ_kZZbGSo_8YLFKWwHytUXMTaF4OFvZH.gu_TuvDJ0dQakheLAucPNc6p128zpNLd1kbnicY1EUukGol3MR2MxbvlIlz9hTizOd5dR218Pp5PdM6kBBu526eWu3fJLGlxF4M",mdrd: "rXjeDgcJ6iQAAwvZDOiL5KCabnRp6eh6CV2JYCz7adY-1744248704-1.2.1.1-FxPT1hDW1mLfOYDJ8icocUGvvUXUAf69u700CaWGxG_cOTNmTC71pS.p00w5qaOX3fbNsfPKzmYtzN7mO40TDW06Ku6ckytF_CpiqnE8J.E7kXHi9vDa9oM5Q4CFzMp.yhTHKotxgo74HDKif4oG5upEdOMwf_lcYy17.z1faTyjU6yY1ByYaFmlc.qikUhKBSY0vexoO.xs12HQVQqjzU26tMWcSKFzafQRml46r76noKNjmjJ.MSgoTS3Ld8PlAuX0TZSYg05RaVNwzETXM96.CDTIDx5W4xdeGmb5IhCPSmYX979sZKjpHMOIJyoOLBmNRIPt8gx5GHPuw.KadObg.VIf3GsTjV08fn9xk51e_Hh97GbF4FTJLw17XxFjQuehF95x0Z1jjTF3RdXNHrtnkndRMrTEN3h26UfjUtjLXjL8cd8x3d9HWLAzGDrsETUXdzxuKMZeJ4bvbFGbyrD3XsUrMKsEFLQhUCwwhTgNn.wspC8uVBKL.dJKMPZ9rlIdbbkA0ACDXaT7u1mN..qsGq3b3SyMdeHCfA104XV9ogKlltzJMiZ7zCaLULnuWx0RNZX70mnEV_yZAHkKC7K0hQco4QX69LWMoOQCLnAjMCcNPDIoCEN6znuTKrVRuqY32pTQ6_lR.ynbqzI7YZPWinOb0tMEYbPnGtS82tf4dj0vqGBFRykokfqy6vYxsNffyAGRUZutMqPP9pncofINmYXFG1V6XJiG1fquXtG3Kz.AMaw2BpE6.vIXPAu0kKL1afnH6p3i9hmQHOFj7mlNlQEAhk0V3gNGiykSbjXY8WEN8lI2_y_fYx12dd6G6SejD7Mlwldjoy2QyoxQi5aCS7rW7ZkCNn.vDAKUhjSGzgtq45XHP6HJg8_2ffYSlFjaEgjLdLuJ1V3zo7EAblybfGtVSjzGEHaoKhhSli3kgAWUfa5H7ndshkZi.b9fqKFUQnMAJj9qIxg0KF.aFAJRvppJbt_DS9wiRgYsBdD2DeZQTYtIM5LKGrp7FwGTBEnjJKsKZ58UViF.ttjQ61tLM5PqjHju_4FC1LJfTVWFETg5f_w3am5epHeiJ8oz356E6GqYeM7owY5MqwhAQDsJGJBl1HVFgGeyssIzVU78sRSnZ_smSnu_I4DnLiHUw6kY7jrj38q.q3E4f0I5tuBnV3vlf6xByvaDrDBRcElcV0ZEsJNfRyjVFjUwNQFMNc3DUgCBZ9LyShBJyvoMBqdCFgqjRPF0F.COm0htTUxoRz9T2MPsd7g8DfM0JBUGQZ9fVrfBvtv_rP.e2_0hLomrQjXsOm7SO_WgOYCmHv67Ti0GP.qDtulqJajYVH0awAgvfOHVY_xhSHUP8W1npwDSbEm7ooOjuIa2uWKlmAQ0UCgGxedK81pwkC.kln57dRwZypO4xVfuQhDoO.iW73lmasZ0BkVQImKBnGINbdr4figfOTx8FKWab0sRfhL7YJoxF1GM713Rw94dhGdUP5QxEKcA6HDUhT_WGs9gMkwHQ4shX3b5df4zw_BB6pSe66n.jY1Kfe5cdf6OrCRoHDKCQvvkzbHoiaCDisUgz7XjkebSuXjQHgHxA.POqCOz6_xodtcdM7WU_1yN4eFfOWS93Plr0MvUyoTK0HKQAfh60xgp.fogEbEI2RdlJwiyR6w7Nf4bm0bwBylfFRA_22_EerRM7MexLhx0pcdBH.VIer8gkICfp83uAvrwAzH5PQUejhdUn2WI_og.9cU.JUgGvcFN7fXLyAqSz3d9Ccm9LlVJ7drw0N5Yiry6YMVpUz2VhSkY8QMTYplnTfJ7DeWGVRWCoHZAcNXH3Hawcidbz8Q9TDvn61rLsT_UBnkEQoc9M40yNorSWQE95AzTp6vs4IUQwYy1LMxEniEsTgAbgoBojV8kodIK2l3jzFbLnisudcyDvmVRGdrlEU.K4nLDx6o1cqKbhqmzglgiZLXpJ1QxHsKEic21Mqv57Gc68STOPtkeYSEePWhknbsjfuFPstXjNpy8RFm7APAYrBSboGlxqcPqbdh0DbzVbq7e"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92de7c832de4cdf5';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, "\/?q=rf%3A7553588&__cf_chl_rt_tk=q1NGiyttUzhptFjPLRYjCQr2q9nzDAPs2H2Szh0JkzI-1744248704-1.0.1.1-usAmN.nfvUr.hXd8Og7evlAR0T92IqGB7l1xiLBjiCw" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>