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: '92ea4d2078f4fd02',cH: 'wnvARIrqWbh_J1yg326rPq1zXkObXKlCMOU6gGubg3E-1744372592-1.2.1.1-wrTua9eHWw9LP.gbNhPCHATI1Tr_1.5W1JKQFgpEMM_3xRPV5uuoeOPmZYQX46Xy',cUPMDTk: "\/0718.35026?__cf_chl_tk=fYwhDyd7JxNCdet_nVIXa13EcrpQIDz3ppyxxE_iH0c-1744372592-1.0.1.1-rMW0zR7CIghaplWryFT5619bb6X0NeJ5EHteAh9K59c",cFPWv: 'b',cITimeS: '1744372592',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/0718.35026?__cf_chl_f_tk=fYwhDyd7JxNCdet_nVIXa13EcrpQIDz3ppyxxE_iH0c-1744372592-1.0.1.1-rMW0zR7CIghaplWryFT5619bb6X0NeJ5EHteAh9K59c",md: "_LIYb4waLiqwWsCqzN7aGiRUBx7MsusREfKaFdvnDPo-1744372592-1.2.1.1-h9banwjuSw1apRRvo30s59ztmxGmYe9EgcJe_aC_Vcoi6skoEosCj2If0n6fC6ipgpNK.8Bs6QmkCoXVtRGVlX.AyjxWRD9WgalQi5Wk1l4FPX5Vt7tkzwo2VOJyv1j51L1MW_UMYKtFEvnvGsoEEsPK8tQvU1IjLOeC2KzrswLBPd40oK8k9iO2GkCS1Z_9k4Q4hExxOum7G2zqVTG24Nbqh_j.gMsGJLR8Vqf0xgTT4y1PZ34jPkYqsOJys2IdqvdjTj0y8.uV_WYyvMT0ZvldIyhLXp0cIlXNP7pSmCyZQkrGCCDPpqclY4FiUWM1EVe_VSZnSPeA_ILzG.it4PV5fo28NFYsVSSmFdwlGHWu1jbtv4ul7x.oVBBCGYk9bolZbnWFz61kt2OXdyVqqmurmumGTD_vZ9N9ioTBETZMbvpw3BayiyDHGUvMWxAiPMY6xY7E8D8R5jcy_Ip2Gmb43r_.jxwtaN8vf4lm8IaCIJxqKYz72fDRpCchd5b5d5tJjP878mUn9N6TULD0kTBr9k80O7y7NT1mPXTpA6kmbLBlv0IRY5xl7WtFKAsp8QegPc6tO5v.1YNXslj.XwmSiZaH0a7ELZ5DBuuNfJWD4ohaIaqV4V96O4AIN0BWgrG6qjwbclFFM2mLkOAbh84nvoN71jkXH_G7I2UZnO5NEiwiy844JdqRshPzOLKt_EHWmf6FjvNk56JY6RShXZvvZXBl8kr7qAJyguDq4nGAVHyYwdosu_TC5agf448OqNnZs_8j1uXAKuSn3ELi89rUpJFZLkRMUgEj_CoCpAYBuDYWbxE5WzDU3J4UAoPAhs_LtewW.IFRC05djTPwKKKSIs7lLNHb92vCNO.wYiWuvmE_DsGRDXkTgAdC8uLjVEBWkPgTojJubxXurWjSg0hTaGp91TF0bwH1rzHRjF108jSf2cPJj.6Asbm5AgvScQ3k7oTTGT5dWqUVElKu.LlMywnIZ.Nu9hwTUCTlQpEl5NI_mpU1ejXFq7eDWOgSatde8nLr47NRtlkURSkC3QUV3XB5ctfwWXdmNJl97zntXhmT0X8EGEh5xrp15.iS4AiSOcPXrkI38ZDpny8LJPUO85m4yqLSFXMjUJinAc1cpNRn0n2aqajnZdhpIgMqfsIG6dhLYFDbT9v.49fDLtHkWyhm3I9kZj_Yp9YRmH9nXpE2PYqembstKWbgtBRj",mdrd: "Wma3ccVFXRt8hztsgYfu0ezFJb3NDkxg3TEp0uF75jM-1744372592-1.2.1.1-bMKYgj1CglHQFtKkw7nLKCcTuTrwpoOQW6xVxsgCYIUmE2XdlOC2PMu.2I8120gYXbAuDuB1w1a75Nrkx9AQgZwrDaIEmfAyuU3q_xlVGJvw2ncm3Q3ozFuMEOxR3jPcX87G5Bb7PrNyrtZYreWo1PfbW6vwsvDCTByu8HWa10FephwWpe26mtWODTMAqXTEoMHW3M5eiYQWkm3oNeqXQ5ulA4A3hOXbVJfe1gDGkOk8nlHwCS18gGaG4CItKJDHTxI0AseJoAkBivaZO55zAz.u32zwwMCR.52TJhNUkQ9Z6YgNY4uWUMKk3nal_F4IIJRgfRc.o9HMVGRAwh0QJREY5VihtDUhuDq9yqci9J9WBvB1u5BK8JJQNeskdXbYFSZRv030YlQsQnvJOtOwoIzYwYTE6ZgKKSM77g84ehQdt3nDJo569jxRt4Ib7kBzUeu70q7X9MfG.4tHjdM5QXyRNYErM0YVIQAeUDOLotrYgNWD4Th.F5M4szBdi8e3yb6HvdEh09ZCVvJakR2IHWqMZvR9.q5hMsgg8HBOwbFGmKAlOgP6w0uwuQP9By4bhFa20tM1faR498X7ec9zyhEV3NrefZDpzx5_JzrSCc3YAMaEPXZACyGvRP8r66AZE_ATAjQx5qZwNeLYvSo0McnTezezPSzTmeLzltCCqgBZlIHNbMbCK0.RZ2XOm9S1.t7BuwoNFnjB94sYSftgG4LIvtYLuRgAVDTkB02gazTtAsfoJlYH2u8HvPPLXhbZqr2I4fPp9E4cQ6nlregA64NcShZbNtzGzERxRvXtNiJ0DZegvxknNs3ZafTJCULwpUEeXoFyIbr4r3V26378VHoys1028MkuZS.BQ8yARJM3VWbNKGwsH5hW5vLGYvP7YV9yX0EnVmXvQqyvc_JJQmcjBR3RhCkfAf9V6iOAQIXrps2RarbY2aMa7jV2cwo_dpmTfmQU1GYi0VVk0q38Pct9ZA16fwbOaeeplPgLe1jc2GM4I2A771stuVVsqxSQbYbXE5DIyWx3tGxHK1il6TpEdJrV9ARbL2vCdA42WKec6VpnkkcsnizDcCElmZSDsq_ysoxHQRktpxNnU1xROKRMN557V.d7KXiqK51tuNjVB_O1yIUY0XEU6kjrmRhRW2tuTFpl3nYr9mAjYC4EznfZfu6S0GJh7xVwK_4ZP2EGT2nMmG0uraHE0Fo2bfbF.i.qiHayr7ZhTx.cFVXF0YuPq6VoyKb19wFqCTuwgXWmgvdqhWCgGWhWhMm2i.cUug9LUzbIdF3zFV_C8DAV.EFPMnaRa4qKOx8AAhNLP65k5.E8FL8scAqKLYkdLrEP04HhvmZ.RPV6UMlsPtokTY09YMpJcz5GZNXxR0V6UIkPtDqir70setrcxQqXjAC.TLnSxLuo4LyclnWeR41aawSNrrW2adrSQ97vDTdi6zo7bG.4rnU73Ydp.1egRrwE.RU94Srg_rAx9U1PcZWwvr4qVEKFZc5uLCHUnnoL0VIcqavFIHfAh6aKNlJRwr_AGYHf3kiIjItExhZbigBcBDg3SFZzam5soL__t9A3GsnFjkInAPtU.qzPRAYIjpwjvymZ8xcUpEclawpsZP.wgHxh1yMx1tSppDRQaXbpQllgJezsAqzrPwHgYy_hkWPXTpW76JYH2lFnJCxkQoTtPPY_8oiA88NvuVHY1qxn5BiCONXlT4p.Y04N3T648UPMeE7dmb2fdoWPELTJxDJvSRuhdLG26xjr3Xftskax4yy7_ORdS8FRmleS6LxHicxz4wZbMvy.gU75aNKpXJp2vHSTJADrrIKBttHVT1BCWXtDz.dTmV.zZg9lBU8rWi254CaJgNfCPdXMd3LtKHO5sA_v1hwUXzs.Hv8GPDuzw6jXVDy9YEjgnyOd5hKkBFyIoQa1E8cKKxpHmrustUMjj0a2nHMsU5aaLwfJg71cbrtV7RzbuPglhq06BnSxr55mprA39rwN4.fLEIsY4a6yD0aqDF.Mpp6q3qZprRFjaqK.9KaYCTrvXn.eEiuVsAOEawYueR0Nxr4Gw8IZdF5m.g"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92ea4d2078f4fd02';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, "\/0718.35026?__cf_chl_rt_tk=fYwhDyd7JxNCdet_nVIXa13EcrpQIDz3ppyxxE_iH0c-1744372592-1.0.1.1-rMW0zR7CIghaplWryFT5619bb6X0NeJ5EHteAh9K59c" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>