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: '92e06521dd53d47e',cH: 'GiPGuf72Wu1iboq9uEQuf50mvVJf2PfD86dg2LIHwE0-1744268718-1.2.1.1-5yi067CPFUOphQYgx_6WQ490EVwdHf_UZqQYrikxLbqTWTTxhqKg9pGo3ON5vW2x',cUPMDTk: "\/?q=rf%3A7536282&__cf_chl_tk=AUcM0KoqzKFDcwvA0q.YGzzbWRCoLmKx4fAGfM3pSCw-1744268718-1.0.1.1-.OHX8PEHFn2DaIBWYkco7Xcpw0rpjk_is41afMi9zv0",cFPWv: 'b',cITimeS: '1744268718',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/?q=rf%3A7536282&__cf_chl_f_tk=AUcM0KoqzKFDcwvA0q.YGzzbWRCoLmKx4fAGfM3pSCw-1744268718-1.0.1.1-.OHX8PEHFn2DaIBWYkco7Xcpw0rpjk_is41afMi9zv0",md: "bIQ6Y2NqzaA26.WGto4ut0bYQoIQPv1AvQQQhpppScw-1744268718-1.2.1.1-XGelUgq12aNou2CW2jD.HbqM1ijhFw0GIVgSUS4pZrbwqPY1M4cErVjnEbmIhJoZ.rbtOOIAuiWLyNgKuekITX6mzpLyHyqy_fT8mYyU7ZAg5jhHosPgY8p654MVmeBEgwm1WHU2Otp2CaMBcCcqN.75ZzSHx.CIf077B4gHGasBRtJwpClgr9qCQXpmNs3X3Wq2mU16d8YSKbOKNSvPPPXI4GqmHGDZXMnBfVU4Uu6LKklyOevFu4ULw5RMaBHaVqdkjngKjh1UyOFB6UxQtR_buyE7uX9rU_W5WuhvwXanZby3dWBTMdmez66hcIecp4aoVvfr5TJUM9rX.pJA6YSEariRtzQTcgkFK4r.Q1mvP8SFlH9CeFRQnjjZM922YewlmxGgMKX2CQjFXRR63BP0j7_vyfxxjw0LYiH62IXkfQsbICoNYaeYoT33UE1CfEibN.kM_8RpgAVDNVa3rwAb2IfLKKMqwUqKRRXWivZpvfg4beMIvuPPFlTlHWEFwOv3MPhIX4.t6JZ.HJrk56fh_xS6bXMGvY2ysh3p8M2DJRtganPqzNWKKxJ4syF0WiEbLmGpcZuCip6pV4wbj1Dm0e59v.3rjgsebPqLfkXmyElQtZSSNZgV2aXr64HKI.Mrs8NDRTQrOgYiyIw56CbkLkH29nFLeA09N4gNV1jiIOqOVihE9RUnUAMbEA2Wqqf3siItIF6w7whblzfQWbuEQKu7j6k6Yj8lVBgB_K9Oxag8o_UG8SdVGuqT9oNdvLc02F3GbN5PfXwSX2e_edWra0lGq3VRhmE8RSHJAFPgCo1Bd6mSyi5yErRneynYzBTVq7_5KnE7j8tDGchYKPBY6fJBwBYVZxbElmG5gkGD1th1SzvnJX7OUl.vR7BYwyIuWYLt1sRFVqK1BrXkFy1Mj9VS3BK_UlZ2q6gE3JrvFgmiEpn.Hz5xzT7NrgBigiQimDcqVgFaem1yflDE.R1ANzKYnUhAPONt7SbqoLrFj2K0QesG2nxNvGygp1sdXu9POnTUZL.Daj_mPOZK5Eh2fxsILZRUqlJnOjgXFSadYTqozFyxsEfYNsIWDUsFcz2nJP1cmzhIFmzLmYUIm2DwaAvu38Mz8094lN9HczOggmIjiOqGNC_sg.GHPhOx9Q1PMojDvXNltQgG4RqmWv9TPyhMuavnZX2i4V_1FCvTxZm5gRkkoI9sdLDk6G_R",mdrd: "lX8FyQWJJlqLvChMyvn3XMaUe6o3_cSgT84oL7QCGqE-1744268718-1.2.1.1-z23lesAaKY0ENZFGT7Tja3XURX7LdHooFHLdmQ9Fo0UJ.eKaEZdys1pYEAP9QRg6W9J6_dqagjBJ5w9Na3SdiMIfOTv8Z32a03QGF6FA1cuYUaXl6lw.fB5W_xWIO_oCULV7BGe2qj00iJDCksqNwGsOUh9g0U1NM8zuTz.hs.O0TArodKW.9tWCYXN5m92aoYoeRCu86wswQAJz6hGkxXKgD6YerkkkyPjad50byEi3sOiThOz9wXxi9xpuwLvw1IgBgh_P748WvnOPo.Gw6CSnmYHg5SwjZjJY.W1oCUUyVbrTdcnqfzI9.c739nInlr2Mz4mcshRbxYxd2PETn1ujtZv75mPrAYLJi3Aba7L29LOVikWrvQJDhBbRfkvCZ3XtaN8LxHPKi2mgyKaW2OOP5kPUIVuLICOkErEUQZ7v2u2m3Mm36H2KPsLCtrLn3b4KHeHdg3ZuEzx_WRmEyQL0CLcc.9BZ0NodAGO03XyqYjs8y583vAk4F2Rw5dgl7JytTGTJ2gPWZ4.2Av8nH84vYBiPyZ3z2q.ctXSd4LCkoFqL7cqVSQ0iOw1YoY6sCb58BwgZX0nNoabJ9xQLxNMcKhSYUHQcet7_znMo6OHt6WHdgo9UTLgokRvRWx91le2PtmLIqrV_dQc2Zy60PPbhmFYwqAq5gXjZ7bn__vjuB8rugzs_Wu8RDPqwq7QjeHI46OokqrdrrGnFTM5vZe39ikjEqfiu8ZZzRGHju7xU9VKZGrjp5coq5dr5PmQ808EwK.P8QrfAEVwtcMMadpHpKFx21ILwdXOCYFPPoZ.cgDQnA40IvASW8iANACy4YFxiIIQzPPQDgg1c7PkvKxteOYSWoHx_moVGALiMSrhmeBy4POmE5S2ZVTt9FIfhdnlD10ITb_b66yjqHF9uLD0XBMTbMGPbY6_OHtDzCYN13Hwqq56MclUVrJMQ_3QN8IFHavpxHkWvOJTLF4K51ICd0pd.AT_apN_DrStYgcz7brrqT_sBboN2bwO_uDf4gdxcgsf7EYE53MZkyw7IyXdTO9CBNlTvppWVKFPIg009CpdOOj5jcKAn.Qcq_zmVkPz8F_GDoHcV9uZENWs7hf9pDNlMeFYy123qnsr_hyBvaL2nEsVPwNJ7VmqA2Wa9TtjFDoRL8FaVd5uOI6taWCdrg6A21ZvJRNHVb.HwPhempULYLYu8YSlT_r3d85YoJsWtgTrP7_e6CbUP7io.n4oiQV_fcP8mVdua9siIX8NXokCLwPDEudzsLkAgIPHhi4FpuT2BpsMt79RNCUDK1dczF3GGuMHJ45ko7V48FbCThxxef5FVMgZMRjFjI4DG2FxTaDvby_hMyM_hnls_xr_aWkrl73Bz0p2wOCJEHa0fcjRu523XWYr6Vlo30ru7CYTFF_H8f8w6ySbq7eE6ZsXtX2lpe73Qo9Fso8D1ayc2VzbNEiWWuoxJq4ojb4YhDMzfVJipQgGWyiHNDpDdjvcC9TCW3mgMiR3hQN.QkI15vVa91C6XYKAlrGFA3VvBlKkNiVYiHgta3uSDrArpdh0.K_F9ydhsskKyc_OzX7AHtLFm7EpbSyvoHcTCWYENe2PMsfEoukTfpbfdPpCDQ85hKLnKPGAu1c11.QK2HpueMaVjOYau3VpduQ71nue_n9N8L_SXKNSlvZkgk81NtuqYmrxAxsSpcCnwaPvWMFF1_ueLprMvQ0_0LUjMw9z0HnFMm4JW_tgReM5NeNItLFsRojkZaSIuBh_C6GNvSdxPt5V_GVXFFCUUQgLeVDNDiuzoFfzh98X3eGubgkv07r.DremF4DpLpCJZXVA3MRYeTuyS4UmXHWJmsjHqi6ipU2s0yHSIM26k5B6bXKTUItOd0Lee4ueFQRk2ImnPrMGoIoCUy55orUsYpLuWktJFDYe_OtFBlRh.bkeLSW5Nw6NdomkFyxxoEVhg04p5zHfhzp4_8Gc20PPz0oYAaMASZVofhHEaRCSDiVhhdQpjr9f4GCTZJ0TNYTwK4wooiljXXqHt7CILVnTT6yR41s3O"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92e06521dd53d47e';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%3A7536282&__cf_chl_rt_tk=AUcM0KoqzKFDcwvA0q.YGzzbWRCoLmKx4fAGfM3pSCw-1744268718-1.0.1.1-.OHX8PEHFn2DaIBWYkco7Xcpw0rpjk_is41afMi9zv0" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>