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: '92e84ea73c7ff936',cH: 'FMDMVNES.d__OxpVi1HxWRbHSWU32Is1ENw18IILCtU-1744351683-1.2.1.1-53uRbLTNf7rPQgm0p5F.opt8kUqwhjl7NEWtrfAB1c9sfh0MX.5JKer9cvfqRsHY',cUPMDTk: "\/0463.20030?__cf_chl_tk=1Y7EVYnPwWmlLyR0mRPkrUA8Xx0YCYfFMDEOPZmk73E-1744351683-1.0.1.1-9c.kHVD8jth1ReX0U.fxjmc5Sm0A9Mm_CNCvH5o2g_8",cFPWv: 'b',cITimeS: '1744351683',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/0463.20030?__cf_chl_f_tk=1Y7EVYnPwWmlLyR0mRPkrUA8Xx0YCYfFMDEOPZmk73E-1744351683-1.0.1.1-9c.kHVD8jth1ReX0U.fxjmc5Sm0A9Mm_CNCvH5o2g_8",md: "yIvZS0yYZfMUTVYaBcnbFtPD7KYrlkKsb7VXLAhx6z4-1744351683-1.2.1.1-oYa7okf3HTUlsbciIzq47ZtlIZKCn3e7lQ3Ul9H_o69lU6UIhgwrJO9zrpVNOocCz4A_8rOd3KIL5cw1elem4nfWoMs3ZRgDv9qNrAGOBHaiVgq3uLo5Cl9Wo2k8U_xCaCP2rvX8Y3yF3BqTqa1i0WxfimibP_HaC2INoqM9aHL.1cK5dswf_vCbf2x_nUXHT9TPes6Ub1xnzYjzDW07O6NeCHDH6mMuMJzssFHmCwneJBL8gj.Idu5x0Y1BVivbudMzgnTOxNSKj4Y8WWE9Jpb35IJm9T9f2mbUdZMnivReG4VES2cPgxtK4Op8MJnm2liOMiKhQgovtNT2oE3flOGe8C5AneBrBIhrWVfShUfzgr_IbrY_28wdTzc8H8ycX13iNpomBd0o2X.z7dH_cMXxtfj9zibQWc2nOhlxUWq6p5f5.hoQHNeD31rFOJcn1uJfe3UIVVfNeB_UdNul8IohsKfSfz7U02IP7j4NApv7mWtZbJDmmFSHq2ALuAk2ocIwMgGgRnK_W7QD8IsRNojaxBeU8ZMB5ExidEfkZZihZ.UeJVdzkmZrjfE96ura2l.8ifiJxwXJQMkR0JAPP3VIwrf0yth_X3Y46rbpO8k4g_3J4Y_ghXytTCoSSOMzE9ji9518NfPPonYZvksyZ.EJi..SU5TJoiyXMQme7CptWu8spgN4.HPLlWXnr7P1LvidlOIXKo8E89Jnn80qTWqtysyO8A2Kk0kcfMstEF7gz7K4VZ5DhYEFX7qkThpXkZmjP2V91Y_qOz9CMT4goruELccA2wEVdnaGhc6.veYGgCZlCH8G74tTtftlS0ymedYFHX6Ru1NjZ82CKh4yau._3Fs_cNSnDq1VrHoPi5ERK_0CQzjl0H6V7tKVz8Y.yR3ZQwoGebOzPkpaCxZ8MUx3NG2p.msmHpQmWCFR3qBHx9_iKJ7NJZLHPyOrWM0VFe1bB4BBxumghh1BS5E1ZcMt.o5LkMIOtTNb85lYSppRvMxxkwvX9kqCu_so_WONEHvEtezn2ezWAdMBzOWtgyava2.i9bw2D32kX2xll0LcLgB2iOqGfhzX7TuVwT_JUy0WKiGDsBYNae.jr9GT3rl2dN4eVPKgka9SImZeVhvNd.aZRUiD3ep7vCbvnYObo5qWdexgZigttJLjDksLiCcqkQBuj3RsFYrT7QO_f3HqVZ1B23rPdBjSjmMvPGjc",mdrd: "TBa4x1xZ44bBixSC9_s3oRrXh..GApuMEAPQnLOVW0g-1744351683-1.2.1.1-Ye3H1dYvlMTzpknRMM3LqPMO3meWSj4kxVX7QyysJ6yOdC2L6Bt51ZeUEG59ou5miKA0YA.OjCwB13llIUVJrYJfXLzDUkLXFYLJJ0Cdc5JYoKiyWn0fsdWeE37ACRTK4i2pXmKZyaVFVmZyhIakNlmgqIrxbz2kCrz9a8PiOcgjAiABshb4Ys7k30K8QRBQvvgmkml23zmFKHEmzKt9AOTt24nRkw7wK3JJlBmT3GGij0psOXkHAxDi2krwv.S7xS36bL9SdxVAen1OF7vEb5WAMfGcHAsNo8axvx6E1dAn5vRRxE0r98dAf1_87z1lTrJqgQA7LwhbOmTHIZSCCJapWhe795bBUUtreXVG_KY6UeuLm23TFmJg1dM2WxcZ31li1azb8IxXeIK.WO64PJvrz9cbKtQRUAsgWVcynp1OuOOyBndUUrkN6WMuSBsaJAxfFU0dYjP3YbMtJnwrTd1E55jb_SRSAYj9BIK4gij3n5rh4UBLVaKoasUQsWfxN9YInhvUdtkloUE1gx9.hzspCUty_CgUGXLLpdn8az7NJPnWe2dd893t.0Upu1J5ogidwBKAs4lBD15AR0sqgEhWh.R0VKN4CZ5Y1fnzyakd5VGtFq5pTFr8fONwEnK8trNTY2WYOsJi0qvEqRlJCbsUX9LH.JqbxbKw9xdZAjaqqb.foxv0INZ2v2.fAmHihG5nAjlb.APzH2XRCojNbE46muTVtcsIrL_fuNrAS3UF8Lw4U07zovWwsQg7SNCX6vGSLTOEWCFbKmV6fWTaXwc9OGLdYguG3GcdYg5VBSHxyxpe5HRisOpL5XjMQgVJcST4w1FxhwrqsAcVLvT77kdhizxCUEmp6yRYHgw_lhIUNlKMsSJNkR_hWDNlwpykjnANdEJ7F8jd5Uk9PlQMuNDcsniM7.46C2Tu5CKpcO87F5JcMBHsjltwnD2WAfMtgRnaQMbUn_mgFxcKjRS_M9ZGq.yJ_fVTGg1fZFGBqUt5szgYnM6pHE.r1yZAUFi3vvfWZrEE2sR315WfAo.tMDwOxC4dN1I3gfQ241Uvqr2rJv6uaK0tmx0ki5mZAgolyTc46M9IbTZA50bLPJOpYSKS8BAg_oWiGM5TdJcVl2oUPvcCyhQxWY5UTKm3UXkyvFJNWaTz9zEejmqZ58A8lgrLxamZPok2h_ZHY9vqpRRin4qOcl2g_QKdnV4r9Crk2XmOFxh8WL6BOwYCFdgHkXDefW9YiORQOKRlIKR5YCFR7cDuSJxn6tgmoBC85cf1wEhUi8_ZKZk1DnqrQzmKaR6q1AecGupKb65C3rKVhW.lq5WPi6DiOLN9Hxc176as.DpxCfVvG8vG0_XsTGfea5tkKKLwlEvOr8ehv0s6vIvbOEO_KUr2q0fWiYLRRup5QSX.evMsDJbKoAdHCATqIeOWaOSPK7aFkq7xXiPZSmKhj260nKqlru8HwvUegpSgdwgnmeg4IuiIAVWnQYSa1u4B7mBsPAEIMCAR40L5FBWcZNo8EO8eaz8_Sz9dfoJOhT92wQP.HdnhAIspzOEUFlYyl_scv.CXxVkvAAlfBsGPwySpT.woMCDiAgJa7Atvio_rFG2GA0EstVJw9wmHAEuOgz1J8.xoyoBNmOZ21irwsXG8sEBDzPMage9lDcgPLlBM3rniBS.WQyF3I6MxqRm8saq79sEY1PIDsTWMBYrOqqTwsVvfWmDrmpyv.ym4CnsZTK0Av_Pa0gRx_Ef6KYmwOVTiLPH3LOfvj.UGjSonxcaO.gUdApu58vbMuaGBbO4CmdRIR_xwFoPWZXzAGChEmUxESqrVBpGgn_wMIhHQ7Puj_MtsYD_6ip_n4N_tiEsHui5XvE18IPEKjT_TgmkcSp9QAgb7FeEqOw4NE6wiz5hg_zn1ylWB9PKsy49691L2a9HLw2t5mJL4kAysVPPMIEaDFQNx8BvKAmzNmJWVdyM._Ab96_6Ozv9N_2dB9gFElZ8SehJeoqofFr8iwsiwOeV41DJ973QT9u8LBJ8aDAdDkAJn6.K4h9xPad7Zh73TxKclR1g5OGKhNGfs.w"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92e84ea73c7ff936';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, "\/0463.20030?__cf_chl_rt_tk=1Y7EVYnPwWmlLyR0mRPkrUA8Xx0YCYfFMDEOPZmk73E-1744351683-1.0.1.1-9c.kHVD8jth1ReX0U.fxjmc5Sm0A9Mm_CNCvH5o2g_8" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>