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: '92dc9acaf99a9d6f',cH: 'sgATwQfC8b3lTUGBuUePo.7iB.BJ.FsJsOsc2TSB42E-1744228973-1.2.1.1-wWASRua_t6jhpooPle6Ieyy8W1xO0VCbecOPs5BD1ZY_v.hTi_nLU93liuvzo3xN',cUPMDTk: "\/?q=rf%3A7454056&__cf_chl_tk=vh1b3niJrOCFKMZh58kE958QxqTzSxQswxqAJFfmAeI-1744228973-1.0.1.1-yzltTfLBOYWYckHT9MwgLZuviAJK6riLEIdFPfWOLiM",cFPWv: 'b',cITimeS: '1744228973',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/?q=rf%3A7454056&__cf_chl_f_tk=vh1b3niJrOCFKMZh58kE958QxqTzSxQswxqAJFfmAeI-1744228973-1.0.1.1-yzltTfLBOYWYckHT9MwgLZuviAJK6riLEIdFPfWOLiM",md: "FzG7roVKgPjU_q7X.uneukAA1ayc_4ILgx3jp9eXEz4-1744228973-1.2.1.1-iPE3RQ5pHxC9diqNMXrezhQAsPZgizyzn_oYTKWx.IwzI7POfLqjt5E5TB7hLqzcG0nlulFELY95vs4bxKjcXnMMJLFgmeLPrIn9hMW4ZLxCCDQ6ZnYm6aVOZPteJcwvoZSrCKTgLBHp_d08_eTab2Ll2PZACWuHB1v4.Kf_hWaAL.W.BP4vjGaVpuPqzj4Y2i5VFCcUAaJWoIYhr_gDmt2blhzDCA9m1_3engo3TVwb4UYe2ydXuGqsSwp42_Bsqxzn19Ly4U_BS7UGOoSgGay1FJxS.WjEJrDucG.Y.rVyL7gsPC2DrchDfgdY1P3DmFEJtCv9NzGCUmoyrgusR.0srxOiOInZbm.2iCoPcnzxIKpenAZ2YMuqzE1Tkswu5drxXHXn4S50Ptrwnb44cnkVLWVhmyDebl3u7Xe62KeilhZZF3Pk1unqEJZ5TfWXgkkrfQvSph.eChnWUDwa9MZFm5_l2T0Ci2DrzCsLt.4HReHJ_fs2zkoFAKFFzV_gcgkZ5Er63lisKghFUKREsouJMKgEaM2BexeC7HLf9AjdqYObjVmnko7fFaKho9dSliSLIMXiTDW09h3qDf55kDEGiQV9YcMH_evINM0XwDsX2eHBCEOqbTMUBnxN_iO1dC75OBv7BvGMZ4JBZUapN8LlYYlC3uxm7obsaA6JMjJE9cDDrrZhhGrMArzX9NgsAAzEfjdgjH8WoZ_xe.kxuNpBQZUuT2AQzVc_pB2bPMFVK8DpxECCTTPyVdoMpohM7_lqnfKZBRjLjsXZa_B.2I2su.jNwDPWIY0GZfolJH4ltuE2S1xm6wjQLh89sLTsZNKgefq5SRchvllTG_01f3E8lGa4fldg7kk4BHRA35RUhETNHH5aZzetTOXyth_GxeNej59FIN2mRmKYmW1cfL9LRjwANScLmEffBiKFSJna2ojYURENeR.r10YIVq731PBhf85fkvIRfEfGBWsEQXYaheUlGA0qGd8qkGDklNEWiNzkGNNHipwev2OeVyFO2oEmWXIFR0UPR1MnIvzBtWo2RsIWMB2SsVYCq8c..wTHeA.qdGc6s74enswiXYuJk6vsyS_JQQR5rR4S0ejCVENnpyp9EN5S6O2hde5Vyi6967Qbj535hKV3qCoF7zxDPwsqowqD4klvCv0zKPRINFzi87b8lQu0k4ubphvygImaFscBdGrMvMy_LDQ1k18D",mdrd: "Md9_LnvG.5HdBuB9z8Pyc2nzMyDVMScGuT2VieJLCUE-1744228973-1.2.1.1-Pg5g_3ovY6GFyk7Q_9w5B.93OkNgExquHTJzg.EzxTw8N7ku6Ei8MowlXBlj3XTABRFHWOwLy5QZvLyeYEVYYuSi1GgrHdfHxb6_E92B62tKdldTJm_XLrgLYMFjPLpQEjwutEUkX9M_rd9_ZE7SYHSan2ff3x_9hclp8DzZJX7GYPK7IF4gL.jUSKDGwpUTs4B5OlHU2RchXid4Rcp_xsMdx5fviWRcEp4j8m8XnK9oeHMMuIN0asoS8GK6DpayKbJqCdEY5Ozl4M5jtxrjQMKiUadT0X_NLXgxJGNPvUF2Pu5.yIwffZXQSPcyDoOCl5rSVNKCVt8paTHQIIHZoK_spWXybf0ZLYoSp.LXIx9OcY620djlPISHY2rRIkk4v85Xo3s5D0ZX_te9Im1oVDfo8Vi289gN3W7tVMHi42W1YpDrcSWgS8LhCf2wm8ZY7JJAkZ0wIrXJG2f.ipaumsFg2UZa0btwyRq_PMEsMX7PJ6EtI1hNvTiVaUyXEnKw7Vx04XCL.fvSjkOkOy4bS_YTash.Sfz26hN.75WDD4mzmDLuuANp1in6IEDhqlynz8MR7zZ7VKaSbihGaPFeVaUwMV.YbfUXtC8eL_SGGgzFAUPcrseojnKJat71xB5wHzAsjKU1R0pY6G1WoUvYlsSLJ9jMdr.TTgOWWIC2JPZUpRRPzjpH14NgoOCyfqjTxOB8FxZ_G85nST4EbtUYExcKWwWvIJxFyP9QvFS.dr9DI8M3nelOFq6V6aSj6T.C4iAybL6zU6A7SrRDXF064XltGslt9YUKP3YMPAr3FUAkeA8rZGsCYrxp4gXdynm7LfpNR5BnvEBn9bXDiezL1hbcGAAQ5084JBDC3JiPgJbEG4oiwQD68pMPTM04nwOUIU7gLCK1r0QcmIevOTgxf5SrErM1elbgJKi33xpvzoTO_KBbTCX23tavo1TvpFQC.TWcicbSB1g1kPOtiThVjfrT6CnJcWkqpc3Tsjrb.ANr.awk952bWXnswkmUM5yBgQH2U4Fy7yAKYyA4ZvZrV.A8Qm.FnelT4ZsMsSv8LbaSToCY1TI7Gk_C3KodQ6aPaotbuuzTUmWD7TepdYPHau30UzJSQv11WpvLZRhzbXDanIKA9i2Uy4Wzc13Xby7sRI1u4qOxaYym.ekwvYCHKQ21VG8fAVzQO_qRTouwDlAgqBw9KX4RGlo5crBQ_a6zcYIXB5wDGbRCTWrsYCb3yQ_4znaQ9n2BhRrM_j27rBggZ7RJBRfqQzO58JUjMJmkatBgcAKimeZ6MAQWHHbaSnjr5KR1JtFO2Y_EAZKcQ_NQOqLbHIGsYQXMOOR.m0gBQhJefqe7p0q4snpGbA9h.xDzIlU9gIBBTR4U5Pz0FCnobqq.KwSQdy2H.m.oi4AdCrMzU88M5aobcUsgPqYGdISsBU0fHtobdIAIOvvtiFKkPCbLvfUNv1b3DITDV4dntPLgebXOsO8xK5dqo5IKF9UwqlV8829qnDP_q_5BuqBMZ97GkJGwcPbspfQbfTbY_pHuWVOwh6DxWbVG_32OWr8Y2AqHgJTlitsxYbtRye9P4LjEj.En6w_mJ8VCyDnBDJepxPkvMJGoJE_VeCqZOAz.GPEycdpJygbFXPzRQQ2RFtKJZ_qrArJWvfLGk6yRsVdQ0uAfE1fQOZuHuwEH7J5b8shXmaxfwr7X_ciAZrMcVJXOx_H8qPfRHa3rc7W_0a0YZKVJPP78Mrznsw5HW.3SP0K11ak498_3yEFIB5FDFsQLvC7dSS6dBmEu4aLBrchFN5X6pF.uP.WsvyGOgu_uAQTHlQUfVm804odK408.ElxHve5WBz.GV2zQSi6sD4pwGI37nUmCcpeKlFDZw3GyPam11._kkNnOnPdswpbOcG0LvYiKeB0rAjywZ2ie3hr6Qo5Av9ifcRthJN8sIC4qP5n6eYCeVi1Pf3tzU1uY0I3.m1SfrWyjIFHtAedeiQtKS_1dHgKpnTR3MEpx93sTLdK_3E1ZITs8ZbalYLIMYm6jEo7rFrz50WIpd53MEfOaFtj9YpRie_Xo7tc5hQ"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92dc9acaf99a9d6f';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, "\/?q=rf%3A7454056&__cf_chl_rt_tk=vh1b3niJrOCFKMZh58kE958QxqTzSxQswxqAJFfmAeI-1744228973-1.0.1.1-yzltTfLBOYWYckHT9MwgLZuviAJK6riLEIdFPfWOLiM" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>