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: '92e3b7125a403fb1',cH: 'LANApqfOP5asyHR7ECqE0kc7unss.tipmxkvWSt_hLI-1744303531-1.2.1.1-EtPPIkMNvxVLvHkEYibq.YOH8lkTSby0KkudRNqAwDy9Vh29cIKLqR3L1oPSLYUe',cUPMDTk: "\/?q=ci%3A1219622&__cf_chl_tk=IPgkYwTb4AjPlgiNHaQGhurgOx0M1bM2SLtXoeMkq2Q-1744303531-1.0.1.1-bMDLeiy3H7l8gYHsk9c53Fkux4GY9E06LChzPyOJdrU",cFPWv: 'b',cITimeS: '1744303531',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/?q=ci%3A1219622&__cf_chl_f_tk=IPgkYwTb4AjPlgiNHaQGhurgOx0M1bM2SLtXoeMkq2Q-1744303531-1.0.1.1-bMDLeiy3H7l8gYHsk9c53Fkux4GY9E06LChzPyOJdrU",md: "7_E2_z5_hsmcsdJBmmLTosqGthftdB8yJAAFkMKOyJ4-1744303531-1.2.1.1-30wZg9RBkp261yDnozM1OoGXrtJI1PgEazhq1BoZgBtcNNB0JxyjXr3BGtYvYoyb161.po_nbGx1djfvolulWjOYqvQz8X9CpH8kZamjy0kiqXWEvhIywMig8HAYL_4n9n3jYaDem5VHKLZPIc5G.mUxluVKF1R2.aS1nkYdLka17vNTff33Dd8Gbh09PTU_SJvQL9guYGwCOhqNLVGy24A9qYHBqP6J6_lc2O2o32GuFztmcDGVk04d7SubxnxZWSLMyHe5hU5Vv8X0N77QXMgc8rrnR4s5JBTpz_IWScphKnL1A1Kv.gFj2Ml0Fonom2D0YwQ4ttpm92d2YWIBIqrTJeTTSdQnJlPhlKAR0fLosegn0poc2VGEV3Rz0BHcZQs0tlf0NxBq1RuOXKx9.j3kOlYahGTqcyZ2Yscud3Uqr8Gzntq263_BvycCv1MRvheVexQz3FMU_mD64ZDV1d9zYOkim.9bj0gH.1mYxU3v8BcU1TwhQaIafE20NFjZzqMjvCqKng0b5dTQvZDYz3EUHLmPKe8C.psvt_2mXBipmw5HeTv5cff4uUYOKOMdkgqQOA0iy.FkgNZQz.MPzxmTTa5IhxcgHcoSuaBszrQfHxB_rsxUIlkK9KY5CGznlh6H64xx_CpWLgPdx73EeZaEdFGfOnCE4.DzKVRtErXLZYh8VZe_xiMc3xS9wghU4bHsevPLKmUJ_0yBqzfwYgwYMlv2R.D.p8BM6XqOJgg9dL0JjYpmv8zgN_JWZZ_Ia98bG6hTayQzQ3tgXg_bFmXVUvp.waDewMS1SoUUxBbZMN3rT3keJAdLvTLGmEQ6cDDOy7ZNXomvhWe0xzbSZP5Xxq.FwuxepIsv952ZFJKodOJO_No1Kr.XdV13JY8hbMARsWikyiRBjAXis7cbF7rEEBlYwx3bQjAGh7AdTcZi59b3rJnPYT.ZcbrcECw9NBV1qF8wNCRUzq19xU0ZHEM0OgN3z2bjYNX5OC_srvNz14pjNeZ4OFyK5Js6dTpmPL9Zg_qqQcMoNE152WSbA3hznpWbou5TvLzrPMBugGIqGITPaHMGNLbVW2E7FGs.0t0r5r.VzaypMlGD0vGFwPgGmGQOzK3MtnEVStAvemO5bkucMr5ma.DGi95dYBdS9ujMo4.T0sRvqM4aqP5rp7kpRGLLbP4lphAa2HzOfUijGWHVO2n6JQkUz6rtkjvs",mdrd: "ZC4I.Y_4WTIZQV1r..5VMqxbAYUsCDDRzL1PEwANLNI-1744303531-1.2.1.1-owgzVrMa0qHBbky.XbihHjzAJJYFMUKKdCy3ka2IbL8qtC5Od9Dm1gfUJ8.m6QijDDl..oZVqAyuUCNaMuSMcIsZIZbEmhRA6jwajaoLEvjTkm.vhfTDQrzegqE7PWkbPw_qo4lj._2d2N1HUxy3Tk7h8HK_59Q18iAgqijynuC6Unm1chN_xSpUHKd2CdmAWpfTKtZ.YFkyqYSnfFkYbPkkRZCyKnfrqioVX9.GWHu4savToJ0A3KyJomtxJ79djrcF32eNNqVddmcPDkGbo1X2Uyr2p7KOMoroTUXnGkTqTdaIntjplq9.b57FaPeiCaYOHAJWs5TrA2B9RTypa01XzZgW3WIiVw5DcGSSYxBe65K5EVZ85On7FuKWnQ6A1DSPiV5fazua1chXYs8WqMckE7vfq4XmHaFHZKo4GLD1F7D5ZwIpMjDp7VCzqF7HhuoLAyN_1myQuySa_2YB9Jh5DuYNoOxvodG3ZnfqmfdDqAmK1YAj5a9DZ1Kebar030MS0PJSL8p.rYCHXh5m6m.5gXIE.ywTPXqXhfwFNXrQyJwDU3AhVpD4p.OqlypShVMSxlik4rog_nxaDiZ8CaE62jc8U_wpgPifOb6P2XFjwZz9Z_U2gK__i2vqIRT2sqY9oh3DKhfZTtY87heNY8J5eUKImdCg5qrLjUdmUPRxcKcg6..dfgUSQ7vvh1AeaH7sm4buCtobsA6.hHSxsQC9WPKHe2hG8wFWpYrBLMrtGdBS3txW5uPbCHshiVXirpH.GWGvjcdBC5OC_oRa.KgEuFqRM77qut.wmNz2qih39YbVD7tNTve05NdWj_s3Y_7dSPa7Jum1HMrCLXZfVf5NfpG4FTFI5KNWpXKLNJRPpeGOncygP_cslOCW93aA.ec9uIKFXshvegunGxnJF_t3lF4ffKu9j3oskbipe76XKGnRbkKXCu9xueJsX8ho_5vNSLJURhGZbdIP6YAgT6sMULxUTWyZSMTAy5q2u1S.xCrr8HOEjszWYKYGEbOPoSqvOp_Ou5PhcOp448bzkQLDgWl.kw5G31FpPKTioVhU7yGnnKn7XuNEpcAZJXobWkx_xQh96OoELxnSOaojdcHplyc.iHR1ANxG1yyKlC2tnplcj3fkM8seRID0JXbESxLWnnThkgu9Sk55pKjE4P1wfU6er4UKHLhR._7rR7SI9zA6L6BomWY.SApdpcTjVP3dd9XnQ169J8v._kycWsOKdmnEFQ0PbqkxDGpOYIGkvfZoiyiG.LmZv3iI8Yv0SKdQV0SJjQF1eBzsNl.htWksvak20.7nkupXXaMrAWugOgqYK0vNrHZf99Dp.j4thEJOSZkUh3.OoyNYnf3o77RP0HX6hrCrmEKj9fYe8s8fBk1sA3zP_XGvPCC8LIQNZjm3B.wAE7P8prt1AgLKeC3HfjAROSekZJlaAapw00kM6bUUfWHXHTb.4VlxMUxMxIaYul3Aq_iRRUnqQMRQjZjsq2YUNd43y1IGcIECbHKhpKUDrUfqnFbS6T_G6d5U6qRod.xWkXwMnDXuNoPxKu1AK9WKCr079ZS0V0R9MiWQsD63rj0G_w.j.KkFFN_a.Doke08abAeM3FBtktRCG5NSM54bm7ZFkLHIknW5FZ_Ekocd5krBjrLXYo62l2JvuMtLevGTcxU64uEtGXNQmUw9ONC2zzm3XgLp4ag6YJElKuBB7G.FEqnzdr_VgJ.mMNQiy7Zu0fjMviTKn5J4SjXvepz9ADDC9_GuLhv2gl_yItzFg6cGS7uaTxldoNnoZfwb017c9LgVzcd4qZlPTc09800ghYl98SxyM7rcmCXgUQ6OH2B.zbxn9F2cztzdjdpsHKPD.doGkArzyz.HmaRXb1U9zrekvMEJaVl6WqOlWCpsPHPDVgBIo.l0yuglsQF1WrgCuWIwYH.NLZ28ISFwTagwFkCYpAM5MsE9yVdO.W8kWBs5Z4irHTpIe2aP1upiLQqPAyp8M0eizcIMjK.yuj1OGNSLG_jt4B9hl9HEBz2zHreXcv4J2f0PXE4Y"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92e3b7125a403fb1';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=ci%3A1219622&__cf_chl_rt_tk=IPgkYwTb4AjPlgiNHaQGhurgOx0M1bM2SLtXoeMkq2Q-1744303531-1.0.1.1-bMDLeiy3H7l8gYHsk9c53Fkux4GY9E06LChzPyOJdrU" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>