CINXE.COM

Just a moment...

<!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,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHdpZHRoPSIzMiIgaGVpZ2h0PSIzMiIgZmlsbD0ibm9uZSI+PHBhdGggZmlsbD0iI0IyMEYwMyIgZD0iTTE2IDNhMTMgMTMgMCAxIDAgMTMgMTNBMTMuMDE1IDEzLjAxNSAwIDAgMCAxNiAzbTAgMjRhMTEgMTEgMCAxIDEgMTEtMTEgMTEuMDEgMTEuMDEgMCAwIDEtMTEgMTEiLz48cGF0aCBmaWxsPSIjQjIwRjAzIiBkPSJNMTcuMDM4IDE4LjYxNUgxNC44N0wxNC41NjMgOS41aDIuNzgzem0tMS4wODQgMS40MjdxLjY2IDAgMS4wNTcuMzg4LjQwNy4zODkuNDA3Ljk5NCAwIC41OTYtLjQwNy45ODQtLjM5Ny4zOS0xLjA1Ny4zODktLjY1IDAtMS4wNTYtLjM4OS0uMzk4LS4zODktLjM5OC0uOTg0IDAtLjU5Ny4zOTgtLjk4NS40MDYtLjM5NyAxLjA1Ni0uMzk3Ii8+PC9zdmc+);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: '92ed1213ef99fceb',cH: 'BB0Ip2YRPjlESdCz0fjphPKF2POfM3VFi_fT3uFiwqc-1744401631-1.2.1.1-HAQjMjCOIWw4wY3Vuht4eo0vMMr2ids3rosj79H59rP9jtO358gEJywx1CBrw5nn',cUPMDTk: "\/authors\/li.bin.4?__cf_chl_tk=h34zKxbCQlgkVPm_ce4nE9EiY_IqsRWMEXwrZs2CE4A-1744401631-1.0.1.1-TtAbZWZBgJYfjstBn6Z7.SHZl5TMu6wn2p9SCmDUiZo",cFPWv: 'b',cITimeS: '1744401631',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/authors\/li.bin.4?__cf_chl_f_tk=h34zKxbCQlgkVPm_ce4nE9EiY_IqsRWMEXwrZs2CE4A-1744401631-1.0.1.1-TtAbZWZBgJYfjstBn6Z7.SHZl5TMu6wn2p9SCmDUiZo",md: "dhpGCXpHh86jN8F4zRS4_l3Se04krld4ViguRaGBghc-1744401631-1.2.1.1-tfKCCIG6cKyUd07qUFteP2cK_BasxGSa9rGUKIPElAviq7Dc_Zvt1CB2rkwv2jhmInaaZVj9bwbK_TRl9WoR9URhjSPP5fE2zwWn9QZ_JLUs2e4ckebThw.Jh9hcbmYKKIqezTnH6whELon47ImRmkcMcdKLgYyboFXJcdt32qn0pIubzDiVnvz9Cg0tffg9AVQAY6QxDXAEY3mXEj6dpKXKezJDjN8uQh66QwLonctlZqxV8uqFDRER9J71HECfxzBambNj7VIvxJUNILgwyganQlWI8SIESnuXAbSPwrLj9iJLhiEurbEoShAVvTTALhRJPy0CTUU7SZkaO9f1o.en69F1WJt0a2Sf9SBYYxHvRAcyuJ4FmH8GvHJI92lCpbLN96Pj0Y1nkyRA2HeUQ2bPH7n96aM.7asMW.HmaWyGoWSMHG4puzQarl6POLc90gI2ksA4OAmq417fa5mdgAXPKB1wx7XescoIBCGRfVEOjhqc5Dpi4CF3CNnqtnmbaIsu5GCIEElvgiqLucuZml9elA4m8vvStYCVWLyvDXjKfTtoesTzBGlH8tFe48SBoqBuQy2TxuozXXT_pYSY78fGWJcAGRMM9QcTxEtS4JnMQJmcrJkg.gkjJr7aKaDLW_LkfwxNPmJIxrGxobjLMFlGSeXDtDPgOgYeE0GwrqtD7uPRvG4rtqBiJeA6FXrOkmel5YHPd3sd79C0l3P7XcLs5LCVjbu4Ym3Ww3DouQMXS6RODyGBiflvEB94YhUs7prEGrsgsgJZflOklKZIwMiWMqkSm4ydBjiasE1xuRsr2GXuo2QHRd1Vs.oAa09lxjFi7y5GLwV93YnbVylouizClAtwVT6K0Yg0D6OOpA6hpcULnHxFzYrYhe3B4hotj5I1KsMzwp6ZOVtKYkEHiP0D8WeW4pq8eFiyt603qGZ4Bu60E.k.1dERcU8NkK1Ar4jKb4tAMNDVEVJcLZsb97rvQRfjI5IbClD19Skd55LEvViSJB__61VESICLqM8OTrip6.4vxISZrKn3UXwLFnjS2V0a6ePJzshJIp2QARCy4GWmu1xHaDjDTvLGnaEwarR2HLp8Siimw30xNtWFx6XVRysgHSCCamv3auypMRQgBNZnVPVKzq0IRUHdT281ssxcXMI.dJLIZ_QSlmEu4PhXrJjBOtPmT166XmNwiXNYbptg3_12GMzGxSis2VJ_7pgVUx97l78sLts9ENMFNw",mdrd: "W8GbYYEpgOqAIDYWOd7AQaWl3aZaebpFa2zC9DbXfMg-1744401631-1.2.1.1-qMIrbIExIgfgMrOGlh0kfo4nkzps5XlSszyxCFt6uObAu2ukxc7vFfzzdwaneSKLg6tfwePJ0SRy2GEjeWGqFHtU2ROjfrrO_HTmg3U2p2Ic8IG4qznnUSRtngsdhsxCJpi7bBkKR5RwuVEBrsIa5JJS.TbfQ4mM6kjT_w815nK0kAUbwlctZNTvVQOfJVxjUSiKb0_8bnASQpUpRXzYG5YaLSR1txhgF.BN1IEmNrNMzZwg6u_dXWWk.uyXSJVP5ib00dUV7Vi.ezfaJLMXjh2fyE.wB4LiCkuVvBxOzLNPNy6z3ym3ygEDGIeYgyqll5nqLKO6utj3Oe3EFayLZXoJAoGJAzGGfwIKZAR.hvcB.oAysD5Gtk2vaGBVR2hv38POvgA8qvgXFs9QYRx.WXDWPv_EILHFn2WzSKz.0w_K2IzOLtwYuHhs.w11QA.ODbMzDEJjgwl9JjApFayGxk5bpn_fU7l8igqbcHbWSELdADJrAoxszmEUWNaFj0BFOtOWck1OF7SV_4V31t3ckqPY2SSvG5HsDM_TJ_lmAHxI7g5mJY.X9Kh3.U37K3nA8j84r1VwZzbovpUNhCw_WgA9GoUsXwMcC2pOYSaPLv9Sa5tBTkLxnZb0EHxaFSr0FUQjYC_IIcQmDmkqC2dkub2guoVBgqz3LevLhyYS.PphC2zFKSAY7YN8RZstTLD0EgxqQo6KBzNFXesOV4tehe2pDE5jXrHMclJ1q6iOFEUm80ipHIRTVc8fd1ld64HFPI3QzjGbhIYA7MNARVLFi4P28.SzlohHIB25IIYAgCJ2UdShdNkgj4kQabYR4dTgkKuTUR6f6vQ7yeyd_SJyPsvqQmSk41ghrWw1IMEkVUzOTqBSpqcsq2QxsgsaQ6h3YJA1SsfQnak2.PoAtHECSiivIa8u3jLvCapxXKwCnDirKc6ZbFX0hE8P5zkaEDI.7kArZgdgzG4KqqkVIs9UyOYBiesncP2IWfGln29GIXC8VF3Y8aMI02udwGrrMxLLWawnfAlXxMiFzzDQEV90YCGCDz58C__ivpKQn8iMNAN47XQsnctuExdU.H3FGirgS57fhrinbWMSABPyWG.0UDfJZytz7FCiFNs6S95XJN1noL8Nkn.LkFMoxXkFZ11aim_mFmt5m36c6zdABq1I5BkbPdPZ.wPeEjzuFQy6BZ.aStyNXW1HCVX6Jeptl6xbFgT3hgZWLpVhiUFFq43ZRo.cf9vHeALbaCxJ_YvlFj6i6mEbhP2k_lHuCcnuLbJ9lDMuq9NIKNakQDP2S22NZvsQBuesWkQ3jXSZoo8vHKD0oPNaAjJxSAbLL5pqsJuGl4IE6iFYt2l3ajtvPAcwcPvHloo8x0O.SMzCZ1hjOiEOIt9VUct2IECkhpcw44__grknGHL0y82Jp28ZZYiX8tfOMm0sk1MaRUNhiVRG.JBZmttr2iYpgUHUQbXkICk.ROI.UxMUMSonBwmlkxP3Di3pzEq8EDkiBdI0soejTl.c0w6Il6GOF1P5rUAaN6Z0DVUJqy9cMrD0UULBTSDfotzh_ThbOsw5zQUqI_m31Ewrs.uCraDxHv.N4W_FDU3uY57kZZi5IKNbnjuiYiYor.vOXgXuvLJebHy3CTOHUSvUzJVt_M9edfwN6lPa.Ro6F3KjvF01tAfkDsTZ0FaThV0G0FlsTwR17kghPTXWGYJPABBMtu2KiJeNnPxI7lnWGU9I82Jf3IS1piO.zqj.E6xNtUhZXpZKTiRwihCOSjpfzv9Oq6TjH5w9zJUD9F_GIsBhj7fQ55Lf4J0vq8ToaK2aTR2LiVbJVn8LBGjbV4KwlXdpFvwLAug6DUMTQR1XyCoH0SfRc4BWOdu42b21yw4o4dtkMuf1sNBpakIqtsyvEwZ1kQdL1RiSjx4ar5ET8g_8paTEKL5k7Ieoa0b6S77_AwRV0WIKcY8Qq9101YjZF70BdbR0VjZefTxKcprLpuyYlfPrAi_0jxpOc0eSejyi4c9v0n0jVgIuev5oQsd7zzvfB2v8fTWd46kBMFT_"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92ed1213ef99fceb';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, "\/authors\/li.bin.4?__cf_chl_rt_tk=h34zKxbCQlgkVPm_ce4nE9EiY_IqsRWMEXwrZs2CE4A-1744401631-1.0.1.1-TtAbZWZBgJYfjstBn6Z7.SHZl5TMu6wn2p9SCmDUiZo" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>