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: '92d4a5c46ef53e17',cH: 'H3LkSA54JRXUy3V1ctHdnUcRvfzUAuGBRuFeZKkjbeI-1744145536-1.2.1.1-f02nCyKCWxTMGg_kTf0V1K6LdGQag_mO62R7CzaZ.yvNlAJKLhqbH_v8h4YC7hJa',cUPMDTk: "\/1507.93108?__cf_chl_tk=lXLvCr.f7KioMpvD4BZ0Eev6oa..0.M6SdFNnXS0uDo-1744145536-1.0.1.1-j856jVFOWkCNVodcgS5mjgbOLxR6vqwUbZCW4atscFM",cFPWv: 'g',cITimeS: '1744145536',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/1507.93108?__cf_chl_f_tk=lXLvCr.f7KioMpvD4BZ0Eev6oa..0.M6SdFNnXS0uDo-1744145536-1.0.1.1-j856jVFOWkCNVodcgS5mjgbOLxR6vqwUbZCW4atscFM",md: "1aA_tlbXmdqcbaC17LWonstTEIe.UTpnqXpckDW.3lA-1744145536-1.2.1.1-9jNINWANFWQYPpesAB6bO6DhEt3pX7tu5A52ox89KnQ2bkXmqvgEHOpHOE12CXny5svuUsF5AjmiAmdWpZz1VtCg2379gnAaDb05Xiy2feUClYcmVyM94Rw.gzMtbLVYh9UJr3bDD3NEVDM91lJJFj94pnRdc2wc.CUselLfNVnBZRkrhoeLit8YjbRX_sDovmHk3pwW1xFHh9aADjGcA1GtsjTwsx8qnAgb_sbK4jvAwbs2zPqEMZOLg_AgnskUn_50pJc6lo9_FUcR7LqXXnAfmeHCvQfLSBhtpPCqjPPTMYvpbxwmf_1qiAao2dXTIG3JDZyAUpiY.t31fiwFeHeR1ELmfxcsRcAWtqFO._X6eVzYf3w9moXi4nUC6rKnS_riy4sKvs85QsGaKaICq6HtKBm8EWlD9766qq1gK9zymYfhFiImjaHDsi66tybFVEocHRxBCttoMuGLCt9hifv.dAYSKkMSm6ITu9RvUHOzdlAnlpXZavmRCxzkl0rbV0TJday.rw00k.qziGG6l.wKB4d5wL16nLTPobsFpRsxPZ53GrS8UH.SvxZZieQKL04qOfdqeUdZ8lPY3nXVk9r1sHMzMctE9sQem0tHrLdT6K4ly7yaWMILCtDU8vVIqYJW2KpNLGiSYhflgDWqJ6Y1Udy2hcg2oJ.EaLa.RAPCxGVpe3gc6onRvFilvgvWobL33QK7rru9nLRsvKEO.mrTUVXITTunrKAslqMI9hG_Cz.78nfTRYumTQHFRI0A5jdSbybVQqNzO3CWz5K2b2Ete9NeeMGStnuOdOgU.QSasaB.OjO7Jlpi0sPFYvOh5.oSn18EG3E_gJl4ujk3OqrfHGxYyoLndYCqii2g8KB2F82L_WrE0DOcG6MU0OWDtVlYw3QMfeObU6ykx1Tqwbilj1ESalIDDzBiKNWDyxqCO81TtewmTzw_25YM6shQiawMlOUqJmfTWeWqkW4ZzCSPRW4xZY_b5HCJhFGyfxI6oJXPw.f1u92nWkQv.GErZfH5Wvib8.eYtifR0UeARVL4MaMYXeyWZh.avJZ52pWsMss89VB4z5_wFXmzY5Wp2acju_lw8JvcsFTGQTtdazyUdk2iaM1.DvJNwhlWDJtu6AlaqlzR4wHVrzocb0uHzVEP32tscELML1qfwynjubIVrdp9zUVoN1h6hBLG4_7gck9d.fLgM8nONKhL2r5q",mdrd: "bDxs9zw3E_hLXCQ8mCpfNFNzOV1dawIr3pPCIQvSVvQ-1744145536-1.2.1.1-Av._aj8Vtn7Wy.WvFLKl2XbhIpuOwFryCRERirabnPKXsZO_HxXpvXWqqvmfBYM8PrQ1aY6FHjovasRHG_9HTvR4CNCFF9IrVavCszlkE7OXyBusfVFtCrlM7XcakcfqRfhkBtdiIoz4KjkwTzCSaCOW.rzMDabMKyOXmB.PcxkSGtFDEoynlVGPzosSuRGhiG6kqKPkuqQjRM9mJIli.eObpkUufxpHKJ.Cz942Wkx0Ip6ZN9K5NhMz0ODfvLO.V30skNKtnToVdr7n8u.NqATCtRdiJnAP3KPKAluoEypKz0lywY.peZd5ycOH0pXo02J.Uuobfqt.lMWAGyxwnfBSquutwKPeimygoFdT9Yapaz1yuGLfQJeeN_gkJ8bIU_Kqfax6vwOuPBkuKLBm3uXmGgqcTZG_3tk9D.Nfz8zjdigchMIVekEKR6P0bF8BD3mjqN6.XZJU7DKPi4bf2fRtYDJiR8zV81oPX7IZCLEX8sOWWVGprFJExN3_0ABP.lPEsWUagoAAL7UXDNSZXACW6Q7ukQf79KxFC95w6PzClPYktTNiYnV8RvhtuAqFluJCFBaTLwVYHdLSDXczn8b49h3Co1a95kMc3R2kp1kIwa4YXYWW5c1gB1F5NASr0mQTkjCbuSZXSE0tR5tea3cPFiT6ivlMVmjfNQPDTOYXpWoKWtI91fGJ0kSXuJReulB8tfORIxBk0xqcPlo1k7XqqYuRll_GDnhDpU1UwfMXTiY.gX1JVXoWG4_NHIoougTw7LxKD54burSFJAQYBho.y7r8ijoKq6U884F3.NYGu0JUo95j0L6SLczDjPSqljXkRaANwN.MUcu2wmzgPyhuAW.6Zb8UFfMKer6M0NH36Hy5.XbkzpqG_8xI.1zs5igbwY8zrAQToE_ZX.8OZBrnmNHmpURT_ciEJ94k0vRf5yQq8vadtWbEWEK.vLW.jnUXVJ2Tub2WOQw0Nc2c8afUMLVA6eH.PFPz9zdpf2DyWgxJgSd4jjx.tHpZoqvlyLo9T1GGWmwOTvqJuxJrQbrdAy38jJf0v.yPC2RsYEpSQ7dpWqrLQ5fmL2l1peLmfNHKrngunLYzV3eavLcudjhH1Nb4BUQBLLDM2BVEDG.RAocnXorZ4Q4RtBoQ.HzSIFZzWacdd48JIsdl5g5fywZuFBMg46ETdsWyx5idbpeRrSMdpJKCvoANuIXEHrc4ivP22JNEuDEou.bb5pPNMWxvWtALL5KSu3J5Sh57IzQUFkkxpm8eMar8jo5TPktB25WXpff6G9iFdesW7YW80v4YanJkH9nsK6VyCFyzdtYh0h_nk7TgJ0bkRqLCOCCwCSFdqUagYfoyfDb_wR1Yon5Gf13zWas_WjKswgZUU7pRMsWtXghK_cToBJ6vdDRmued_BA3aSF.PYhZJcRVly4l5AIyF7wwVOysbLryKB6dLbqx.9x0QBKECkVJWNT40yENuKg1aAcoep6YXX._Oq8wV2wjIp4rm2zLUmSQGyNCbuXTFRyLCZl7FBpYM7.ghnGI2o_hVphE0hlLAK9PzyxKVQuZY9EifxTIqYXiFREANMXsBRa0EQGQnHCRAbYA2ruhyDnNn9B_klM3kpTMTurR45eRqtYNmnkVxKeBomPlMrg8FeaIL_vvu79Mt9n.HZWTXBmBdN9fTsUoblEMjjsJEndP4AwFTmzZMAen7akkpwO5JRUl74FWrWZhfJ13m44HMQDNB9lO5D8ILTbFdMO3cPmWfMb5vH3iCb.MTVvoFsp_BDUx1SlnS3WXAy7WLhyH8tzvaDQKnkCugRV3x5SKP.ncBRqgmARvBzxsmPwzPYoieeg.el37qNa8iLICp3TR0fZ5p_gSS93xrA1bnSig1HHq0sL6_nZ6YKAQscrGMtIlaEzMKD9S6vMq6P_gtyS5Tit8KDSF4jeZ.SU7ugt7rrjFbq6OM3rQYAGPKcjxDk4cvF9XBlOhCKp2Rl1rQvYR5CQRFa2uVK.9AS9b9IgF8Z7RJiU1K4fTyw0NLFWoWyAKhk...4weHiD49dXJ3"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/g/orchestrate/chl_page/v1?ray=92d4a5c46ef53e17';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, "\/1507.93108?__cf_chl_rt_tk=lXLvCr.f7KioMpvD4BZ0Eev6oa..0.M6SdFNnXS0uDo-1744145536-1.0.1.1-j856jVFOWkCNVodcgS5mjgbOLxR6vqwUbZCW4atscFM" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>