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: '92d60bbb9afe4df8',cH: '.HpIiuG5pSWbJEYjuG.Er6ooKz1qyyny.PXRfQroB9E-1744160198-1.2.1.1-CzBYnL874iRuUz5aL7DT6rSqy2sq4XBao0siG7rSwTb24EaJf.uCAzC7MAdXVgnZ',cUPMDTk: "\/1328.60179?__cf_chl_tk=.pi4m1_RS5OAfQvvP1Dpnt3bQQXOQe1iwZ5AqB1sJ38-1744160198-1.0.1.1-qe9iIv166zreTMgoMX4YSJRrcIXHQrWgYfk3cTFq3CQ",cFPWv: 'g',cITimeS: '1744160198',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/1328.60179?__cf_chl_f_tk=.pi4m1_RS5OAfQvvP1Dpnt3bQQXOQe1iwZ5AqB1sJ38-1744160198-1.0.1.1-qe9iIv166zreTMgoMX4YSJRrcIXHQrWgYfk3cTFq3CQ",md: "qr00o3rpQB6d3pUHinr79I8CICgN7Wcmve390ggMWL0-1744160198-1.2.1.1-dSG3byfCazyqZiR3cgoEQPuRrvxHxtIf0CiDaOg4cT95kdS6NfmM0_u4nZO32TW1ajnkFlXIH8.9wO_Il5zNcXerzyZNe1l8x4gfBY8GEm7M0zShGu5JndA7uQ2uae3K0bl0PjIf8lYrbWUcDXm6KNh9ztc.4nC8oz4UHY1QcfAtZoUHUEtkZc5vX67GfwfQCPjmmWV3KBr1kWbV8i4LbEKHXy9bu54kDAm2hNMGQZmah44NXkAm19nb2lnRPDsdIy512Nq0n3IotfPPKzI9NAKowkV.3s9BxvIplrDLpmLLcueK49Bg2dI0vMF1givu5sINCIoY0USlSTzQbtq1613NQfd6L3O1TUJUjkS7Gw6B4.ek_73QoZWlKKg4OXMgEbYBHsDTBkhhNFvKTNLcCdrplLIYXQE1KxRqtsbxObFde0BpcMbB8PqWIVDgEB8zjrO7SUusbFzdNzeUYCB5D8O5noe8lSSZW6EmIYkG7syWvlUNoJv7qrtEuxbWftVh5PrybqRBiBiSxh20LGltZoY4W5tcEkGjEZ.3xW8zBrIdeSZz07_5LgD3k5XrCoJw1Fm1tsK8Ne3oiMFnHlURQdkRbCmsJztT3844100F4Ol9ma0maKywEcucvrctR.MSwUJREjcPK3cBwXCLJmeEQh0oLDFBkuCm4ot1k0fdlcfqQQXvKrbPdf_BZm3w3m.El08o6Mv7z.LVFOGFPXohXZ1nbIcrchOhrUpdRMn0bQuVVd7C4YR9Vhvaw4CQ.AtMS2U9frNNSEUkFzRwtXfSivMi69uFTMR6NYcqpnHytBH5WTq6qMIicMvlrQoKFQVYjmLBdVi6voZmGZKp83QWY7cJvmtPGoUrHsaLw.daWCzaSsYWV5Eml7mRXXJdxOkmUVsNTAGn5dZk3jnh1_eWsWygMcAHiS3H.r2nxR_kuolwlIo7mE1lPznKzQkkSUZ60SeZLWnPdnviI_9PPPQz3SNgQY5GtWt2sEbL9rbHhi40_eXRwKQyWLx.SsuiN6MHwtIehWbHSt7B3bka2h3OzvGzsGIFUUt5WxVNMxn7bqX7ZPNA87Gc8tIm36EfKZkZWzMUCDuW.HQPImLZYR8DRjhOfKzF9ivPdiIxpn8GKvAeY5FDY7e0NbwxwNT6cpOXo88Y_SeLsQ77SjYqC8tS10QfKKuCPUmaa5UGM6wnCZz2YKxuME.t2slinWmooI2q",mdrd: "i1o3y8Z7K6YWj9.Iq6XHYd9DhC5PGtO8BafLkH072pg-1744160198-1.2.1.1-cluhZLABYrHmdDqflQrRMHl2uHtNIqiZH6rYnILuJnsFu3Tl1w.I5RAYc3xhyKR5_B60D1gUoUHbItUuiaeHdCYhi2CryDa2tQvbE_JoeEG.7Y3Al_IJsbUZoiru1OvA4Qe93WL3ej7zy9WTplKGgx71Zyg0EbQoe8PtZ.wy8rV5YIkth3juvcIm7luIxxcqfJLJuennJV6Som4A7FaIsr6P.A5jabBiwbev68XUZCTzLPNcg7Pgh9L_vLFFLXxUgUtaQMJUeX4TNGuih8NSH0UQ3pJ1H6V99Aajqx2E5vDIzbcYrgEUvf3Pn3VIQ.FQUKVDnIvJn.2u3ESbWwgBXE58QXVR_noeAqGQE89m0nFAirn8t5f8Vw1aCGnavJPI4DD7R4nxafkPr01BWWIA5TV0dv8F0Lk_sbsvndMsC2O0NBe65nxFkWM_vTe4.Gmw7_KMQMYd1qZ6K7gAeOBvnCbiJnb0BNaTN6NKdqT6u.9x8gpYmbS1DBtjGSt2YjvYcCLIACEBsRU.SPUPyXQAfqzNWcKUkxxFkzGEtnor6oIX8EbFGOFjHWsiaGAqbdN_OzgaGE6c5Mx2clj4WBKVZc.SCUwCjyGm1b0ik1E1Vmm4DYr7qHbFMPPRQnLCG2WZ90zJJDSrsyHZkOlwUZ7M_NXajuCf5dxhHS3jzIpzvj.dcSi.yWznisAj5gjwqEaIi24SzYQ1uRFxKi9x69wN1MuFe0x7uIoWm3.y0HRc0I7th6psgZeaQf1MVkrHVxIeGS.gr21MzJa0HYQQhPRQucrZcdz6xLgRJy_gbIFLLp7Qlh5L3LpjSQw1D4hue92A_F_nyNZW4Wm0ZX44dcWpHfpiBFELmChG1Eh9gFB6VIV_1e_ImKYjU.pExnDVoNk6LtR9CUiwXtE2FvLL3Z8pQ4Y_e4AvDfqojsxeumbCE_zvc8mDvjTda80hfz_wH0b2NY46LFqk.skyZOT1AiwPdELd325IdmSp1P0U9VBpsn._oGEalpEsRj3660Fco2ckEUTSYhDcka89OyHqZj0jjNeWnDl4YT6wASIF989ZKMJgSzfjUdjzS2fyZAaAOAz58Tu1cEecSkqGjSDrz0GYNEr9qtIzmV37tWkxDH_9nbwZ4bjJB3dkh8_JnVBqTvQ6q.YWJa7LP3UMPWgCqsQ7FG.ivoV3RiIVyXbbsWv9tIHAYrt9rZDUSmbh_gJ6BcLhvBk8ncUyPi_0z5bK24vFdSxX6KKXyX9bRUKsoHGaGtpIWzBoYaYPClqAaFfwDVrjWTMy42jOHK7ohrd2N2pQ5e1t43iVY1kas3rtrUnH3IehrqKRhD6i8XxBJLfciPBRX_x54UHx5xwTB93mERMrs96vbLkAjRPZqEURrDANUy35uxVvMLPCpPleLvm_e_dKO.ZPRMPwRsU8phz0of8JxTgNfGkqcpZQxTuFJ2l3ZGCMauc3gDb5k7BERauV0hrTXwq0OouJG3eAMopuKVj6y5Lin2RjeR4DdrDZou7kqmrvcOol.M7Xnkm6ENVJL1KRncC1SIoILRr2dxkGqYvg0cbZ_Gr.l_RmtNCjc3Bwx5pvi_T68XNlXBal8n2PN8SvN2d2drbk9qqTiA5gI8cgW5VZFEGvQC5u68o_Jb2d6jSk4kRSG.tI7RdoM.7qMNN0JwT40OLXtKy5iJlJJVLbsr8y2fojyg2jYmi_EB7BwpDRyFWRjQA13VZBogit.gbJBbgNMPnk7QL1nJ9x7v_sXXlCa0Ug5UfZzHmrL2iLB3GwmLW5NvPrU_xPypXMKGBqyH6yfV8KLLojVHzEZc1oKPcgt_3WHTp7uD2zp3Sd0i2ruXqP_ywdAloOSbKmpxnpfys6E8GGeJ.LdvhuSZJcGkVxh7Haa5Da2W93.eT6Z3vZoZnb3PTwBpep4lksVkJjL2ZYlDHfCvaHXxko66rnRI.C5z6ZOWy_4UbaSc2CD65k5mR9TcGB98gzffQFN4gOqDojlvFGlngca0PERx45.QH0B59xVHC2xEEqHWEayAV6bfI2bsuYc.BNK_ZXjFiL"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/g/orchestrate/chl_page/v1?ray=92d60bbb9afe4df8';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, "\/1328.60179?__cf_chl_rt_tk=.pi4m1_RS5OAfQvvP1Dpnt3bQQXOQe1iwZ5AqB1sJ38-1744160198-1.0.1.1-qe9iIv166zreTMgoMX4YSJRrcIXHQrWgYfk3cTFq3CQ" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>