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: '92e0fa3ebd6c1184',cH: 'UM6cygyT3DChij3Nnaqlawv37BDPh5hb9lXI.RkIkxY-1744274826-1.2.1.1-JjgtGrO4E3YSIqvaYDuK6PXPP3FJdbsEs3dvh_eQxm91w9mwcuEMKcbn9u9ouQdt',cUPMDTk: "\/0873.93055?__cf_chl_tk=88eYnjuOOcsyHt0Wgkh2pUy.j3dY4TCaHz05EejfALc-1744274826-1.0.1.1-w8_AKITyWp8yeiw5.tMCoTLY7eeMnJeEuFmU4jlNq_U",cFPWv: 'b',cITimeS: '1744274826',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/0873.93055?__cf_chl_f_tk=88eYnjuOOcsyHt0Wgkh2pUy.j3dY4TCaHz05EejfALc-1744274826-1.0.1.1-w8_AKITyWp8yeiw5.tMCoTLY7eeMnJeEuFmU4jlNq_U",md: "Q0GJuyU4fAgx.Qj7Zl3HHj9kw6N7hU7ulu1f5LrFZ9E-1744274826-1.2.1.1-HhlBykbLoUgfe3t99q_00q6.c0GCG3PAtif8pt9VebRa8vd8OLnDzVES37bJ9hy5WuWbtNDrxjn7TmlXUeOSuUoqi3LMO3jgjznbay.m2YiF2AXyxmqWm.uBluzakmA_EeIXvzZ_PnOqV9ztoUwgO3CaAg9mUL53d7OcQp60okFgd7k73jIeDvdYAQiADE9qNdOorROwJ9vHpqoPdcn4Nf3b1d81O9.wMGKpg_jQKj_xEgKbZpa3VL4LDhaHkRVxsdKhBvokTtDpu7FULpGbcIxlVGISHaDOOzvNGo7jKlpsM1lvuNUfZvORwsrz01ZZW5s1MyEmk1TE0oGrlrS45oP6U_cw0hRYCcQabr7jTB8ykoe6bUzxgYX_ZASh6_JY8WxRzdog3fL7xJMJQkuAzBluB_gddkZTEyw8jdA4qnDf10wEcS4EAW889yo9kFUOYoeWvnOyy4Qo9W9tYzwk5ISBw2.nGZyljRSSihqsBaMrwLnPdhhH3gfxmmX6RIgYovj08.SxPlHiCcHnJAwQp2Sp4Dbp_GV08fh0TcLG2GqFFKNPtPGAe4crlhqijmt2AIuM1cMLHJewVVinVrR.FUMdWcM90PuGDFCtzMeiIAdzt4c_bPS6Md3UvEMUwD2x5NON1s_vlhuFAqhLPMwiiSh_uE.PLEtaJD5r.mujQfsXMLvENW671E.NaqAnZ2OWr2c5KcC1uXybVHYWqcIts7oOIUA0y4qbmXbDF6wymuqEijsfQ.d0ILhZV7RMYUQjj.YLEFFB7eKBlH.CxWkEr62yHZet3lDYhI3dXsXBlNA3CqStju4yH9zQ4RuDcGnI2g8OLGMV0_1FGpH_FkBm8HAlNxx8gZOAX943p7L.ykRA8g1qcjWy1Alo9E3WN.iX6qMgjxL4WEioPj90hT3cv_RLLzoNJu2i0ZxGaA6Y9kBI3kpoOHdCvhyE8unxsqg6yuPEgpulB.l6og7FA.t8Y39id5D9mptFjYrmM09EQlezoTG6aXRHSH261JzCN6I6sU8QaEUIbLAPpdTaI.KZZzqxgUuKxjkMYYcZeo_U4jLYV1wvqBrlzbh9suSJ_Sz3jX2c9HbVdIW6Rpe48IT3UwmBHodWWQe_CfFN5Wb3N89grkHY4NwBWGF64Wis8F0mzhyTVqgTkTf4ELvJXXx0bOgQrDPBTP_QiFdICCbanCc6obKvXMLfe9bDV85DSwSX",mdrd: "FRjbbmSoaHPUtNKRpriDxSGMu.mzEQYCFIQ8ghxU1wI-1744274826-1.2.1.1-Az8lfh4MpjRQJWPSAjHNRTEZtM0bih4FC1d0FByHTx_i3n5e8fhPybZMggw7CRcfNDfPmjEgwbrndN2LuAYmhU9sQA3cCipkpvmshCKII4fOQ2QOuytZsKEF4pRUJRGARGw8WifEXLg5NZv1hxuqPPh2dx7rOw0YEVG1u.5T_APRn_vuSmYSC56mvwudAuhIHS6d1cFCGVMlXowSjM88k6SmxkL0lgZxasTUMLQmGLw_8otBbiB_fUB1RRupNKuRbMAmwrrNymWXJ_1QE.FnSDeGdS6Q3D5m7EUyGLuDl0ybVr9RUhX8exTukoprWeqrEe57DRIJLia0D1J1M091yaohnxMQok5cRgT3T9GUYMt__xqQZtO4jlHd3ZypRSo.j1xlDpBm83yC0DyeY2qm5xgzvIJkS0sO3froe.A7U4MVTncJbjLC2a.tIvjw0TMzoxWKOZJZ9O8aoMwyePlMW5quCeTSBvlc2K8iJEvSbwgb8QP.GyE7jJWgB4acYB6yOAgDmrHzoeJBDxaBwGwiqtwstsPh1OWu3Rf0fRJnD_EZSFutoBsn4M6o7LijMYo6SxB6wcrzxIvUVEDLTmH_xcyLHcISLh_I40yFFkUH7V94rvHaHMsFKwrWdYwZ632Hwl8r_5OdAELOz2kRuLLgBrcTBts20llVmEsXgts6P3Mz31IoKG85ueG_V6kF7daKQKcf2um5wXIEAjQkzurDkeDs_Egq.4U8IUVedWphVOkUdKECFJ9lG8tU1pEmU9xyr0_Sa6jM5LAGsZP_Nx3VMoRvQw2W4awXXtOKPr.g9E9ezmpns3CnPDV_URTXDFX24H06ChupJ4zSiPgQvJzICc.2pfe0HsdtWSzMACSJiKtoVHYkefjOvmqHWTS13ufVyDukMl.Xtpbl7qZzfr7KpK6PwyloKB7XLwp.ag3yg3fHBNydnccM8AIpI_8CCvnLCS6gX6UYwHEH.bPYuXzYr9Z4OBiuZUgD1j5xrueuvNpwK.3Hk22zHsCfGudDxTp7r4JCi416ICmJGeQQsqK5hfljbDsAhLlPT9aXKPuHNfpX8JaIAbk_PLFr1gCPI6pNccRltmxfHHb8hMQ9HXAJxjWHKX2jCHNqBZygjOgU3ECtTOzrEY.To8yPMlhWmqhBEBtXwplPZIARynGcxZq1.xka4z4ehSt79kRDG8z_N0ZbYDr5GymYmzdkD0hgw5SkW0XkScKK8whTqClS.VdSaS1NsAhTVa7vTyBS83nSbw7aKe8ihkI16I.uTnrBCsZO9MP_OuDyYzBBbxJBJiPiXvA2DLcexZ_P1_X4rmLeZldsAgFC5fh8pLQlo8Eveplzl26QThvrzhsR.LHDie4BH.kLZjLIDwMgkRT9zcXjLWC2qApusJjC3ntcCDZXxiziuY0J030P1gAyJWXxvp8NcL4IdY8.E6x04BwdQfyjvTbjTC1RNETWG0x30cSmfNJFZJkJo4VxJuvEHmZFNs9qmnvYeJJHSnC9nIpJnPSTcLtkWrgNMwXYATVgIPzSq3JXoCQET9EpWCWvoqQQyG8wYTkGZgsj4mDlfNk4uA8nStIZiQzlndo0TuoYFPODw5zpwTJ5C9fORQWRgBr.psXjmWQ8i_ukpTehQL9qWMyXZHQOP5kde52H8PKYWUVWoUa34eTNtY5XGAUDrRHMc9xaxQ2pYSO434aVSTevdZE9QHVUwnk.f8v2dU2fgpnE86h53PcPxUAPDkREX.cTAOjGSH0oJjNmg6wJLCiLaREYu8BATWSLuCoqtH3tZcXVWkmXAVbkxoZCY0xwF2i7ppr3OF_g6PmMtWSQ7dsaUOB4my2toNIupZRFg2BtQYfglCckluJb1SyS4JVO56FnBXTqrLhpMezO8FHxcWYElaWzjQNNy1dMeRO5ytHvf1CAX0qDnpbs4jv6cCtKCsn4S61jp0sjdJfhjxUS603gQYUG0wkU1OeiuJhQy4PTjZe5h68BcFyu5QKTtY7eLCY9FPZUtAv6jua2vlNGc1VEPxiDMNYvBnVE9ZcdxGUFa5hpfx9x"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92e0fa3ebd6c1184';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, "\/0873.93055?__cf_chl_rt_tk=88eYnjuOOcsyHt0Wgkh2pUy.j3dY4TCaHz05EejfALc-1744274826-1.0.1.1-w8_AKITyWp8yeiw5.tMCoTLY7eeMnJeEuFmU4jlNq_U" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>