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: '92e4c82f58966033',cH: 'bNqMSG650PTRzyohIaMvLOpi4CVFWtGDXBViAcIir1g-1744314718-1.2.1.1-JS7wXyLWyZ4UWTU9Sq.Ik5s42JcmffSzPOR8Xwq1UjHDeMvC56KcNCsrwJZNvLxe',cUPMDTk: "\/?q=rf%3A7015337&__cf_chl_tk=F51qHWqeh68niBgXHMHFusVwKAWOU2IR8q6b8ojChx0-1744314718-1.0.1.1-RO0rbHmnJ8ZPM7F2kOk4GMMknbTGAufhwTFIt9X1lbI",cFPWv: 'b',cITimeS: '1744314718',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/?q=rf%3A7015337&__cf_chl_f_tk=F51qHWqeh68niBgXHMHFusVwKAWOU2IR8q6b8ojChx0-1744314718-1.0.1.1-RO0rbHmnJ8ZPM7F2kOk4GMMknbTGAufhwTFIt9X1lbI",md: "OEOWbsN.Ojn5MwF5vlXAzZD1gr5hfj2TNCPn67BID0U-1744314718-1.2.1.1-X70X7qnr.V0ubNEa8sQfH40nVIfeKDZKLbbLtKOhwj9a51g9yoJJPfwUerL7Y5jQOHg9_AMDr72nBsHnyu_l.IW5D.zQCYOgo9K_l8rOSmoahon3gxpdQPV7luOT0FyxyobR9vlafWA8hUFHaMlKp3PErkjoMg5s80hI9LBDRHN2XeC_7dEpMmf.g9AtU7qS2I5kzxtYue_5oBhrQGHjNTlU891PrTdGHpciIaZVpSWr8i33qHbTdSMoTH_X4bZrenBwDOArvKpEw24VA90rUSGrZBYqNw8fuSKxSlqPOxpRmgJpJIdZbAM4bVRFHgL.IOPG1JVIAKnXOr8QXZCO7y5tJrJl8jiF3cBBUzhYB_YiKQHr0LWke.9a2bSebrys2.IkK8wII4Aflj2f5Zt_B0RrvLlDtAq_nAOI3Qz3QJ_uRtM_TFt33ub44V93mnmR3ew_aXn92v3ECNogFyVNXV2cHAxOB.sZUyb4_.6xd3zzC6P6e18Bo1utuKBd7v7KMfWW7278aYT3k.CJivQtcSwji3vlUgUDX91fExp92mbTkZBlOdBB5.iSx15zO0yHI0lvM7IZPv_18N7aA9sE.R3gwuxL4XfDAC.RMI8l7YvvkJdwgSsHwY91bJgEaeB5tyYq0v6TQpZeOpLHk7d4hfH8A7F5X6sLXA1QJv2_FuPCUF0iWLSaizBdG19AkW36W1pvAeohp5kz_2tIWDx00YGq8G6hKMYwxJK2mwkGc0PqpX0MyASl2I.w1NsqPYeUc6c2MvdVna9NCS4VlleMlTEDtUM0BReNOghV3RvJH0clselFCPd_xRkRhSrWYicCMMAnOHwi451VDf09N1OrjfNYBPSJSTKOQtBpxlBGUVmKCz5sn0xb8XRTm4CvlMWUZZmYqr6r8ki9qDQjOecPclsIu.kJSgAqlPVZ7DNv0ZvXDdxJ_t.Tjlc9L5lnULhoTwwBaAr3PScBKxSmf_Y7W7GOA.WVVq1lZ8KxVuwC7JG.gnId_MECo7jO.Cm0diAslffJMvJMGpHCHffVa6_rGgvuntUy4jAAt1SGcbJf9nRTbJffI2kFY4vg6qMd.UHnLENodXIvZc.hb3NqkONXCOg0OLEigwVbn3wTRWTXDeneIr7_RJZdbcBBB.XWD8Qa9rsW.mJgceGzYx4IHqOXxxrhfb34LtVqXF498ir.x5J09jpCO6WeaYW466hUPCXG",mdrd: "k.qed9nyNXYI91yG9YbThquWs_Lukr8.T5WTv2E0on4-1744314718-1.2.1.1-dGr3jDvp_KqocNB_lsONC.K1Ekqk7TPtOOAUOW8Thw1ECphTMbli4mP8N0UrgtROlHewoTCzivXtUBLnpsoNWmfoCwxak23XMwcVIih3lMokM573IQU1B39dWAv8WxPJ1hWdLOoypAW8wB88zTqRvCY7i8ufJ1i7Z3dA8Q8x59Bfgoe8D.LxOCpshs1CdQahMc6pJHMtP_QDuFPazhgsJXS5.nmQVw_N_uDS6yAremQssiPE0QDleZl1MGNfx_c52VXrW7jZisYjf_VVIQ1_Ug6rtJ_4HjdbTWeUAGpKTl4iY1WMhXEw00WuLO5MdR_pclwpVNQRXEjTHmx7KmXteta7_3aTRRhpODIVMa2ErdW9_5tfo0vPccc5_lbITXFQgFNcajT6Qt5Hx2WveYmkG.PVDGL0.d67kMRBZi089o7SxfabVFnJxp2IIyA6P9vvD342Ne7dCqTqHrvX4cFqF8gmUXjaJ7FdjcxHcTfnlF1h2sUWrBIuCGwPWZLAX8fATGUZbL07IDHtMAW9dxsWDVrApVXRd453hVLvbmjXNSkCqaKwvJ8IB4sjXf0qNYbayhK3F2RZlUXxQywLRPFtd8KsHveVpFqedzNak3vHuL0R.H1HBcS1vuHj59U.1ia1M9u4WOeZ2r4wS5AE176lfINRNcLsVA3En1f9ORq360r0M_qxSpCPd2qnvNNahXHHw07k4JIO0IDQ.2Rc2.ZK55BmTuHSQkpAv77c5R4ucAMaQwfAB2og7fgeIXUlelGdS2Wp_ciV8PZX9F_LLC5na14wxG2XLwiVHspLWyddApMdipEMLW2pV4FIq_qFAr3pyg66F.8D8aU4uuyiFG7bJNVQurUWGZn9WvaiQZDjZ33nOIUMfb3w7.G2rRLvpS0w0hMQSgPpCW2Xh7MfEWNhvQObL5L65m8E9L1oO5BTGIwQhrHKFqOpdMox6asN_0KiHC5NrBBEUWcGgiV9smbYWWyYC2lLi0N5POa9fdi21e_PhikZmidJdeUEWjraoSRk6fyuYHEJztun82zyRK2Zkg5MA9In3d1IQpyzBgTeaG7iDf3wMvxCVMseDqrDEPC4NWsGxDuyujhBs2keR1C9bftvG1tn9Eap2FFuLvU_T8uJ0cVTr3FXA_eXFp6VO66p6Z21W21hx5.EAfEm6L3bVgwpiMenzSVWrTOfYu9Bler8On7thH2fD5ziKt.J3V83fzYeOxXYVQnhe6D_5lDxdQNh5XIxyD.xD8KKvqU.q8Y8uPhHToQ15dPOkmoONWMxmuIph2qfB8CwV2.snmsXp5_rvWSoCBjukktJ9SKVsW7r6ZTixpcnb9KaLKdd9xHjLg_87MunY3R4I8W3qEeP08os0hKC3gBxMDwToJkOQmPSz_oG3mUFAeNhcXMUtDmKPwjjO8rmV8.pJvN2mF.IdvWeBIHnOuFXHEB6DUAfTntBVz1sEJ9ROd3hd_MqzxlIak96.Bt.J.HObdiH4_qw7l4Xmd_kiFjv9xnJwKlGqvg4Sq4Dw6qN1NkOcGQYBncS.9si49offECQ4rBHU.TbKU25rElULUDHKYytW2T8GBoW8gFNHyiiREAaxjnnQSbBP1HUi8mTmxqyqv.J_ywOWzMYgb1G3peNp6w5TG1hptRDiR9mHvr_aY5_WbaE4IMw5S9qTIdMLIlwxILNxthTguee1Zz_YiFKJaqhaELl3Jpr_VnqfKs4JgoiAiiNUchijlw3HXS89Q8K5Y6fk3SEbH3VIvbPP5Q6it3Op9u03KtVT9JJIMdC.OB6vJ61s9_9RXeJxkv7lOHj8xnqJFrDbdP7Juf2gOBLVHTx67dJLXxCBqCepN8uzZxhiqI.q5QMjiif6Lu3PNbwZuNVDXeIrpnQiX9CyN15ILfXJhp4gCIO2bTuUexyGcmNxJMDQyuL4b1F7Q38ekmYJA.fj63T5sW1uIorsIKiMck68Z3ZEHYFdY.tAU4wKaFrdPw3zS6LWoXvJNSn79e3Qcmknsc0CAWdum8A6lfp_iB2NnO5NPur.94ydqn7GLcYx3ST52zFIMoOlZ31bCn9wvxJF8fnFQ"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92e4c82f58966033';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%3A7015337&__cf_chl_rt_tk=F51qHWqeh68niBgXHMHFusVwKAWOU2IR8q6b8ojChx0-1744314718-1.0.1.1-RO0rbHmnJ8ZPM7F2kOk4GMMknbTGAufhwTFIt9X1lbI" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>