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: '92dc88eb2a91a027',cH: 'hFd3DjqzrfnjqnPlaBxwDMxExIbyuN0x2Y9sM.jf9Ag-1744228241-1.2.1.1-peNEsmTqyKTVz5daakezfYoj5MVKRiEDaQInTs.H8xC6Czo98g0kwENFzFgdNhXE',cUPMDTk: "\/?q=rf%3A6991468&__cf_chl_tk=SpWK6AkCURLqxpQZqzmBXoGFxP15CJtm5ZISkza.gCY-1744228241-1.0.1.1-PWY2n0bkx53o.u7EdAxgccxcPFJihJVnK4NrB7aBte8",cFPWv: 'b',cITimeS: '1744228241',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/?q=rf%3A6991468&__cf_chl_f_tk=SpWK6AkCURLqxpQZqzmBXoGFxP15CJtm5ZISkza.gCY-1744228241-1.0.1.1-PWY2n0bkx53o.u7EdAxgccxcPFJihJVnK4NrB7aBte8",md: "AbUIOqkldkxpM20NkURTDg9pgpMxRngMZ.z7pig4ZTQ-1744228241-1.2.1.1-tE0rUZ6DLWLCB_UozkxHjefM9lm2rru2lRYW7kL9HKHbgyX2q..xa0yq886G5NYKDNdFmrbzzcBbS4m1hOIA2Dq41OWZmLbm9ftcIOU6AvQ1TGrAaD.GNKDjtAoJDjKHrFOj4KlX_vWj8CuIudDQGzxjEXR.om9zSwoMic43k3QKp38muaIsYwClVAuGc69ttrtrP8fRKyQR7xY_GRZLGHAiqTWcVk2gHMIi2T_Qe7jWJo3rmP7vCQ746s1Mbb92X4VRrCtFjCSyFdeQiHNPj_nz3l7J96rnT5sLKZjHfYV6SYvA8U7d46tDVba8STpRHPYTKxbeGITjoA4_IQeauDerxKBpVis62qt57qin5LqJUu4Fq0ccldJXDGamR5gdy8YwOa9_QqhPoTkXcpcXHmLXPH14WaMD.aDLJ5XVOyBUJv46zTUH9.hY8_SoKd3DWACk9Q_dvJ_M4b4iWPJlOnvZGOhgdCP1T3rWm7gHz069AuMtVpWKJvczjdFae5oPTAjrrfHHSb1hwXN.ZUhD0JejdDjkg_Am7hmsD7y4W9soklWUIUl281s5K4CG1.aSGTJ2MDaM66e5p1_FKp6OPUIeZZWJ7hywany.RqyA5VrslZ_KhvsuefTeXpY4qNZnHHb.mfl6cazD8o6dvmwVMUu8S6qtuB..UpIlnAOqYEC2RHXH4voGRMpsfQOl9A2u93cy9LNYQTSxWbuosjibrDpIYcCNfZUw58Cl_7hqd8yrWar0pb5AU1e7Ez9tTsQUcncTvFueaYQrIPlDoaT9.iOywFrYx4UORdAym4ZD2ANqr_w0kwraeXsaUOJgySzM_LlTeQ5yHNPQE4corBXPbZm33QMBLedHjQ9Yg5NyN2r6ErN.OpPz46q6ZLkCLPW7J47O1PlsofWIkOylgzgE8Ua9BuQ2dd_KOKK0EC4iVxL7x0EAXWDa.8zX2KFjHNHaY3SsIrKcVifN6gjF82T3C.KFQRjNkEUEaLssNu6KVQjmWNXprBJ.JFlgu5bRAnqE_hMJwzF5cojT5iJapWTk8Nw_RiHNFzFeMN0WHB54yDlWLMpryZE2MVXYvMBdgey.WpceMB8PEyA5hVufnj5rGwtN3iwyuFwaV86WxfaJ4I4B6u2ZRT9LgN9FlARnr_kTLAjTs4vz5biT5RrVsekoM_AQM7L1MPenZo5z6UU_IJjWXEJ5ewmtM9N20focDUkt",mdrd: "1.1okFEBT1f8wsRnN44eWxruJGiLQ66QpOM5naxwmVA-1744228241-1.2.1.1-Ulkkw2aSRWdlf8kUi6buEOJjdg158qVRhS2gmz9drW.OoNCr3.mFX1TOW3KEcfV4L4AofRNyjL3lswq3zPch9YTHl1grbdhN.1L12Fhyrigt1roWpCv5zbnCyULsikvhYFrFIvqybB2AcUVfDSmvbPiGFq2DjAb8CTSXUncfVCki_P7B6qmI8B3Et8fHztccfIbv7L0XvqC7tKBFewrrNXpJdXTljhb4XYIXGyH.wccE0m04y3sjKZ9KIMZ_TmoRcKIemsJ5lYCbct4RiAprTtBtCyAWmrVjI62JVySYaodZPPmUu2ow6WN8bRnQews9UW4fc.vhVPIgHFldUCxOmwU16wtwLP4fGkQnQge4.zJapPQFVl3AkghQFDykl1my_Lcny7v5Rtgu2VAxszR5AIY1.apchDFGf9HnLui8h2UaA3Vg4siyRdJPNtmNRznvuKUrvOe_VBq_iMEl3KFVK5OirQS.2MAnAOcccLxNlLwBmMtL.1YQJG6PeLIrCb2KKT1_ukWk_H8zXf2CTGDZhVJT21UnzLsPW2AQrWOCxEbWZ2VqrnawWKe_CdZ9fAiNbc5o0Nb83my2V8.CGCKey9sUbrM0JS9.VgvpIrLfkCF2e8kE5kXFtnB_qkO9SPs8N0CW97konArNA7C2AYpFWatYtKudHbCF8FZF16O64SuOhkFLdtLUJznKL.zvpxfkQSHV4j0HPZrifTq5u3wJpREwFFSAjEcCsrKkASmh4trSv5Vb_ylvWAdg_bcsTfANvNtiRFg0MQU.yAyKhBwnXBWhuS2eCcTkH1vBkCRzQ5Ga1jrVZ1qjDWQL.aAa5mLjZG2tPJYP_lJT6KLQO9zPqWZIDgO_HVfhG1y8fbWJ91cEIc_ZUtuTz.hnnyk8717LHVho8QzwZjRv4Y39i1Sktk64zFg5ShErhcpIMRyYjM1Un6X1uw4W8wS8a9pnrP_cK3KoUj6a5c47OULywU5L6hvpO5_EXhYijQkmAJI5j3wK8o1LUF.y3zFRnW42AbwaEKm_Jk2lHlrrOK9mtwhLRazMdQgPbnfwwUoRI2k7sCvfhtfeJV_eajGyL_Xm3MTFAF1wG1oe9qb3jpTScoAeeAsV0ODAXCTfFXi3EMMMZ0P6Cdk6MyGZSqDhjrJkxwCVbrN9oRXeIAovvhfsZNn41a2_QOg1TgNsCtLC47i2RTReoLAE_sZYdmQXwh_Qd8f3DLHLSZB5cfBKBLVgoQWFX9tbERoRb8ZOEYdjfnwr.FSKNnWtWXpQyPnJ1iJNtV7GhBDOuBSRRbqy_XjMzCJ2WdBwuf.Q92QMfHrICfn5Ax.OaKuhOzalTJ44d1n7LAceMzV8O51Z5AXTVJa8hIdp6lJCbDrBa.gaJRb8O26NONPnpH3zbcRdcpKmKXA.j3aGIqU4eOhEW2pf_C0oDZfM61Swu15vgDuqM4EfhxaKMyZalCRvilWxZDn55D1HMQaRLhfw2zMvifi1rS09qiRpRrwsbF1BoXc2dwcvMavujxIUIkfQcGZ6axwj5QZl38fCYiqgZweNP2fpoyVsMwxmuol0Ii69NCWYNVNhq0uE_iuY19UWbm5uQXcGP.UVZqN1zslbGJs5x6.Qd7ZMYIoZ3i7Unr_dFnPWa9Q7VcFVfs.AnsC4kWV0ErvNDhoOfzTdtBVmOSL1JwwsheognoRUYQnMkFeYJy80ESn2.aZeUKV_wOIoxLgLZCrKRSV0bx924lCTgB1z8w5Cg0eSu88d5O6ekibkPQ1QK1NNcd3ITJRGMBQgeRwt7XlB4vcnYLG.rcZ8Sgs_.H5nUzi2sMp_uDNFfTJ8sVS3FJ4XP_qXxODHFBWkxoSr9c20_zzKHm5pQuocpZrgomEDwOE7Qw8fW1bEM.K6xNBaJ1sWtLIMUEBJ.UREnmcSK_UtJ0g28yhExadyoN8BclLR7m1FFAaRtwRGaPNZxziWtAj8uHqjMO0GJuBJdw8y4H4hOqVJq3mFzD3zjPfFpAcFepNl.L1cZnhGfPB9nNR6Ce4qYv963bvTT43eW71T6Fal.BFgmyxZ"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92dc88eb2a91a027';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%3A6991468&__cf_chl_rt_tk=SpWK6AkCURLqxpQZqzmBXoGFxP15CJtm5ZISkza.gCY-1744228241-1.0.1.1-PWY2n0bkx53o.u7EdAxgccxcPFJihJVnK4NrB7aBte8" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>