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: '92e1698f092e2a90',cH: 'ySSWEnBYl.MiHrALolsChBSFVIy4TCMyJNBssJOTtUI-1744279385-1.2.1.1-uTE7d8_2wjIzahW7txG0YwvEtUlF7h00hZ6Btwj2XHmVr5acz4EjIwxyxR_nb1mY',cUPMDTk: "\/1222.81022?__cf_chl_tk=QI1E2Fjwf8aZvtxpeQFtgQjl5elt2ah1Ii8DtuJncQY-1744279385-1.0.1.1-BCq.4xVNoVr50IHMJiSOCQZlFU7weXM4QaPEnqldxbo",cFPWv: 'b',cITimeS: '1744279385',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/1222.81022?__cf_chl_f_tk=QI1E2Fjwf8aZvtxpeQFtgQjl5elt2ah1Ii8DtuJncQY-1744279385-1.0.1.1-BCq.4xVNoVr50IHMJiSOCQZlFU7weXM4QaPEnqldxbo",md: "0WVAYXG5zMtASkjp6v6D3QnXZffTNisyL2EBo5_uF8E-1744279385-1.2.1.1-jBnS8BOqIeJgFb4Eg4n17vPZxCg8Qdi.f5u6qtglHgrmIbMzXeDFSYuJ9DtgrP8RTQoBfnC9QgPeR2JstKLunwj_IXYnz7EVjefgSjchqrOQhUK6q0usHfBoMgVlpApuODi_3m2CuSJiOnG3.kFyS_ooXTv2SNJlHeZMHT_A6CfDOCwunZxZRfAT6TRmwCeNoDDArZ2lZT4ap6ifiQKE.whGIhBfgQwKvVuA.otyPcqouQPLLGTGIy6G4c92Mq1Smlbvon_c8FZDtMvrt_gm5AItTJr2Wz_I02VM4PYEn4nZpng_hLDK7lOEbTz7E7__BWsV27jFaJP_RHPYGQDCQY3lqKIP0jAY6b_fJR212ehRTKx7Iwe_h6CwHhJAABTuNp1BbrKnOuEpkEot2d4gh.TY1K7ZyoCC2oGV713MEWa9yr0mWpsUoicUuV8KglUSsAeXX8NPxEzcaDhoQJQfMgXiWBkliShGi9ag7PjVEupFAjqueLtjGXdt9P_DjZEFXEazzJ6jTqF.SZsFdBGeZG__OnhIB04WYZqkHfGRtCWdv5aUGOFhdxLcgyFwKG1AXM9.cILM8X4CdAodkwamqxGNGpngQJKGz.54H3mOxmm1iVU1YzNBCwltfJ_Vz4Id9BwCjd1z_K2ApHX8kD2V8TaIhDSXljTtSYqkf9Hxi.OqPmHq0sjlms458an5qU7culj8DpvGGe_H8ELaOoMyuhtMZGC9PWLrUfup1lMuE2ueQjXVLuIQ0SkGxf45dyXqrLzgLsyTyJJic7f1a6uxVGCg3wu6Ca4K6.QFab7n1nPpcN1xmvtlwBOeCCu3kzmWIXVqOyvb2a7taWkh8C_Qtu.Ycqhu0MNTkapN2UEHBmXcOeoZwYyS5JFRVCrMSTbBHiSmgFjU3gYLxgypIH4ffAnDzXJxDvJgM94hLX2hzxH.hUew1n4oocuhjWqotijsHTIczQ3cMXMKESTJL7xUXy0_u0hf3iKrjllBqpx41.oIipKwjC_xmo_vHFdwqrw8iFlFAcZZbplvhHJDZukDsacTsdhVVvAUJsYeZpTNHUSIwUK9mCDhesI7HwRE.IXV9acRzn9aS1h1FfpuNnKRPZSZfPmLP1Me3JYecIbRlw0A864V8QJV79jzEV15uAuiMiS_dvCDxpRAot9pyyKDQL8Fq8t56Z16Lwu_NyG.DX.umHLd6OgUjiH1Pol2p.XC",mdrd: "Wf014ftWZNf.6XuYGPsKSE1GkP03PQ3MrY8rbMFQwZs-1744279385-1.2.1.1-ZbiNbP9pZiypvoRtlDQ6TTdsvzkhWmreXKT6UPiPgRo7aXselcyiXKY1Bz0uGodlOR.Pz0eDsQ3ogBmPcUIOZf8xnoUrSLQyI0leQOiUygKCW_Uy1OL5DYz13j14wMW6oZ3XHs5mQXWmbfLF2m1CZyhBtfL_RV8vk.jftT8zuJn9v9pReVNrKqCEF0wfGK2LqrP13uDGoLGn7484rLamU6DR_6La0Ea34QuK106jGqdhmNI5ysJR4bxMIxBlNnX7Lu7HVg_JRn71.aurWmA_miEtrOsJ7SQTahbmLeJ67jaJscsX1IIVyLfw_Tj3x3skiTRE9oMdWsOs1PiA4kCYFeXqaWXFrNVdLN_IMdE4HOqqSYuTdZXI.CJwoX97o1lUuEyV5Jzl0phSTWJuwbtEcaQaamp4JqrvMxw9RK__gjJLwZAe.DOyGhLsQVk.Fc13ywyfjICeEd0s80OHjaqb__dlE5iwtVWlE0AqIq6xp7L8MQivr_SHz67EGqGnETJQPdoLsH2N5ISh7bC7Oh056.jdLKyZjElk7TYByM1mK2xwQhIgocPeAG2MegxGKThIlSAzSU6nqjOW3mW6argYlmCyICEXChpBOtwixVrAIlMhh4eJJpR76ICQuFnb59yWpgSifMqzntUT.t9.28whmMYrexEkLc9MvjhnWKXQBQjCQXWOYHuFs90F5f24xYscOOoLFHz.zasa7cLMby.peTNYdkh7gCoxd5gYh39IlTW1SMjExFZdpJQpu12ACOBH5liV_fZi1Uqh6L.YSjwQEEZVFrlB_pevSwGBpL8tqgj8G1UhTjTst8jZMQgWP3wjpaA_WU6BsFc0M0ot7m6XEAznFu.pQwchV67LuN_Nmala.TQpqJmypaB5ewoYdy1WTp68ysIhVMq5YtS5pL3A4qnXsJ_UMteL_tW3kfvVFnNHwuWSBG8LLYw9CIH7C6bh07sj_zJoJrK4hpicP2pNhUl8fxJuPZXZU0r3BBXGt05gjZx2nkNNFMdyzWkDP1urbupgJIbGCwx4fcXtdtju4G5Q_9d.9NgGz4Ic_phzR8SnNjS_amgoVfimlSjpvBIbo4LfnLjGXLKqfiE8RCgUQiTr9fT1242Sq6A0fhKDOb_AAqRzIKwjEWxhYvRlm7ABz17RrBF1zaga2.kUnzIM_z6K21rX0oE6a17sXVq73At_UHpeltk5P8XejK6m4WFHjL6bVU_TcUqB.dBqAbqUvs681YAnZqmD8IDJ608MREeuqh4Rlr8oVJNKuRE3Qx2uxJzHNSuZ6vxTMwrzUEC.cc6pZF9.IH_NbvexKXfIyPM3Z3j6FNwreF3QHOmamT41TZ0717Rwxk82m5.L_jEtAAtd4yKB.e.tqPSgktQxyFUVRg4WrxI9r0yI8V1ByC0SbkpmNB3dz5J4Ud_LxNvixt4Y8u4O5EQxFhqODwTTLPSup3ajryJl6Sb_h6r0T4pN.y0ZOsq42QS9AmLXBdD5qR0pDteoFWcM0pcmAj7JLhyw9ZJIxN8WUxcbKcvLh7nmH85AcAB5p8uXI2.3RK_1fqGSccfvvppP4oJ.zVINdXwtKZEp4zAyTzaPOyXX_CCmUSOLvLeg.Y2B78t7B9Zz9zyLP3f1JNUMOt7ZbmtyyAa0SiOvN1_pNBEsUsnevb_Li8Boz2dReUWGU09izm3B6ERROQy77dU1AIPreTeEIb5zMdyrw3kOBvrLkOml6HiKjWxE9ETTA3LIEhWhPRyX5qOBYEoT0WcLDMzQaVVw2huMpe2XAzOYnHR635loLg8kXoTZ6rmT4Mn6sefIVc.SUrPlKSP1DQsqi2hI1OqWbglWAgOsQ8C3bWd4ey11j9eqRYx7fzfOW8HP42lvtVB1bz5UZrshcl5mkBLWzEcZmsKlwuOAKlj6No05uafffMyQWWIvCdArSNds7wPJB_y3g0WJvLjYQmwlY3xUSvddcHqk1IZxDig14fqLPd2j2.kQgDP88d6EmORi6simrkylusNurc.drjGCY8l66VPXlL00jBaQF6bRrDJERmz_x6iHxwoiqAuYepPvV5IEpSmkSg"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92e1698f092e2a90';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, "\/1222.81022?__cf_chl_rt_tk=QI1E2Fjwf8aZvtxpeQFtgQjl5elt2ah1Ii8DtuJncQY-1744279385-1.0.1.1-BCq.4xVNoVr50IHMJiSOCQZlFU7weXM4QaPEnqldxbo" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>