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: '92ebd3378b245f81',cH: 'jPbqRbSfWUFovIaxWRw1vVIXMzQU6nxIgFa_wXtbkAc-1744388570-1.2.1.1-EDJASXA7jcD8RJhgU.PdzAdYMCla7qwzB2ZDurQFHda.KGj._QocREBpcodRfb11',cUPMDTk: "\/authors\/wu.maixia?__cf_chl_tk=u1n0d1OwO6.kjQI5zP6Q2b.E2uX4vh1xBB3MulOKAXA-1744388570-1.0.1.1-_JiaNHYi4u7Y_XONdAtHw6ubV4Jacp.kT5Q60p5Ugeg",cFPWv: 'b',cITimeS: '1744388570',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/authors\/wu.maixia?__cf_chl_f_tk=u1n0d1OwO6.kjQI5zP6Q2b.E2uX4vh1xBB3MulOKAXA-1744388570-1.0.1.1-_JiaNHYi4u7Y_XONdAtHw6ubV4Jacp.kT5Q60p5Ugeg",md: "X1wqbDqrF_mPzuv.jiWSkgGSv4MKEhDw3YtI9Huc8Rc-1744388570-1.2.1.1-OxVVKgmy3y43uwhCoy1_5AjJOpzKLg8DmMbHyja8Qkv_oLhLR_1Z09rHckCX4s48R1NH_20HhbYfAfQlxaopa7yRJ6UsLetQoyAHBZAOJVXOC.e4ZwpEDJLDw4UVpL6ffy4tmfNGh0ZygiW_N8cEzwpEJTzN3BdZCfINRYiVchafmLbJzKi0kuyFfvkG98K8abYR_myE6UzM2DU2Vxf_0qT2s7ZZNzEzw5D_zFCg_FCvmyBSSEhGVAGearQNDqoYxokLD4xmSyp3GpyVDQkaUdrA7MEJZtCFc39qnZ1LzExOnsGAhvegEMfmzjYjQmuEf7X42oxBdDuK4UTn.ZYDeKkj7w1fiYeiLbjUNNJn3rs6XzI1VlO.y44uCaOxmpfhReYCLtBxm6r.Y1EVbKFCcG4E6W2gCUo6heEQYwKrlwcMtBGCAGcibpvAsYymjv5IvPk_MzpFz8FYtZRYZ20CS2nX8zTsiLetLbBJ7hu4DIcq0sSTLQOhZ_Um81m2IAD5i2BnlsZaXJwjIZwKV60iCsNg8GWk695dt7QiiSRufdwzyXIg7o7ogRqEZn8HUSjzxTXngmvcLi3CV0MFZhQBwVX9xZ5Rd.v28yY2ZEl.9ODiz_Xhp4CTbP52xpcr1R.jiA0L3d6Z7CoNFpF2ErMDzr9sO5G8ufLLttbh8YSc7iNnHaCu8oP2Oor6Q2Yne6W_fwSOKrC2olyPOhczeECNlQxPynib6YJ.KWrM.kU6nFCiiEVRGJtem1iByaiC6QsJiMrgRpnvXhdxhVUzWTb2VnhrdrRzFqaovsitaXVdzEk8KewrGVC1s47dST1Rcq5Hs1FOJEs_5btnZFK41_oKH4KtUPtpSR45ZHwwjJ80B6wfkNAr5CX_fgCA4mVd6ezQarMIEvIUJYsDutBsHfNQ10VlMf656Jy9yodPLOenvYdQ7A6WhEGNQ.cajY_Ju4Dm715pjAmtO5aVv22DhaG5s6acfhuMgDfIT4srRi8DjILixIQqSG_c390qX6WkQk3ra.gwlOHp7qT8eJ0bY65R4TzHJ4QtH1NOnEPLxndXnPZdZL042Nydl_xddI45kZR_5QYtPdJXGQpjTdBRm5UEUIoJ0SWAbjMDa_sqs8zvwZQ9o6hDP8hBRQJgJ9ju2AqSEGZ6gIThA0_UV9q_TyOorVuRo.6F688P9qZ6D6fqW04bFusRSlYr2UcZQN2nSYppKa7fGwBXXJNBMyV363OngQ",mdrd: "y9e.r78loVJnQf79Y5un8y8OY0K5xa4fzsBGZMT57xE-1744388570-1.2.1.1-HuvXjZ_x.3f8dcM0WKlZY.ta8HlDHGbZCv9YL7Xk7BAJGrs_ZmBmuAJ9uGmgxfwDrVBQAMnXE57Bfb2M1JS1UKAOBL2jHvQawidLE.2IbINXHu4_FRMdRziv1wFn8PeHfE3dKcBwBbQ5MWKuE20Gt.E2WMPhqzFuvROLZeeJwiI9YNY1CsUGhPJ8zt2rybVmcgE8yXmv3UkfvNcErPqSyLx.hwq0ylfRhDkpyeE1XE8hef76UQRMUhsEbU2Z1WGwTAW7qC.l6gOxJ02jo9s4jTSlrsnel3iLCbdT8VP_vYhQE0naGs6tmzGIMbfRXgiYKtsToUUO6MG5RUds9O7WRXQj2ggSCKnkZHTkIkhCDG9s_lKzz5Ig42eYJh07Rx32bhs8DBYlESsDPfDrfRfppxhnT.hPQis0NgmWStqdFz9ejaF8opjJ3XEO4gTF6WAJ7LNaEmRFeK07lzAuShkYxKUmG1FQEvPFLEXaLri4NlNZ67_PnEsZ2GZgt22K5JPB91XDVisVg26TiS8cbobL8IY8AcNzVSMynVRbQJcHAItA2yH1uhgPzDkfW1Wkh1mB3KDlo9dH0FcaWZ3qJmqKzNRrWHD_DBCS_U.MXTOGFJPj49bgZCJPvQDhwH1NxyDsnC48NXvsB0JAkXupnS1MF4.um9nAssWzOWCkCvN3CdSEQLMyH0fbvpFzFO0WqGjKkhTv9SaVbuUhntuJ4xAbnutG0oUWBKeqLV7yFVTIwJetmCKJE.thAJE_HvgDywsAoSRE01ye4Nhuyu0pcpZwOIfWzWcP7w7cG7YTmj2rL8LhuYvN26z180LVI2tI.SEqW6oHIzmlVkpOqZIX9ResnKJObKeGc7ybxvnww1mLZdart_9AN2.2R3Avu70WhJcBPtNc7L9bWlMc8VCUAns6.ykgvPA3LzKL13sDEvcV92gTeN3SCrzOkcLHI6BWk73wh9zNnPVVpQmq.jVi6MTxDPAgH0M4DLYL00YFmHQbbkuLGUt.QyTXTejKosLJbSeELWs0v1auVYv384LNCEv9eQHwpe7wiBSZw4tg0lFTVev3vgGw4Id4CB2FatDBlMK_BoqIkU9bfe8ekrArgrfn8yK_wmsDZQpeF0ssjBcJriTlzpveIdLVwSi8.HXUXX8UxiLA3KeRLCJ5Z8ejp7Il7bOtCi213UMlZMyI3EYq5W13XLwyNWf4lP_n9l4I7hR3V2TAX.Gt4Y2qjpC_Z1QqJ4.IeLaEXuSRjTyKFID9mUD6ml2j4cJBhUvhdBkm9snkarJeK2SQzUKN6wsCQRgoN06O5EU65_oRVcSR7KhfCz9ScWiuMDNTUSNxd9KaWsDUWKNiSTkuEoCU_LvZ0r5FQzTagdTeztxtnUdAQwtaHUFUoN67kH8P55nL2iD430ophhx_a5eQuiKrRmErEcgXSstQncYd4dkhS1Qs49bJGxKOIWQ9uziYimZQlJCKisu.saYuHM3GxAM9cZnw2.D3ehylAi_aQ6TnjBmYaEW9e4oSkfzmLRp4OtzDRQM4iW1h5hseXDzX9qeplRfJIy0ginv2QFponK_SjQ_Ym5DjsZ4CceJHwK7plKSUdRotAjvtNbOM5JORsoZ3qZ0y_SPKcSVPevnjH9vZatqYaC.RQeDdiH0HoQGwk.trJkmEcr_yBbcbe3HLhK39elYTSxB1biZJ1Xm8xudRFPeWx1WGpRuCtehvH7rZTQSBmET4qVJ7jqIQ7AdDs7DfT0wNoze7iZ1Wd7w4F.QwSdermGJfypnvWVpERBzRUcaz.HCJJFl1Mw1F0t2wXyiHdLuJG339tnAQDmk0OSxOS8QQ_oTQ64Eqn0BSoohqnIjQILJ0PtPDWv8pQYaxQ36FEJAkhE2Znou7nbvTbgewRtftWQvqsFGZDP7gfdK0TBV_A0Ai0RAHcnM.PYxURaVecfKQVwgrZRMFSBWWE5t0KOz_usjVBMX.ROI8vtVmNSl1iEuLRSzA2IbYWBFE.wMLepBjh1KV0P5zxxIDcl3dYAYFEmM0NdlOAtyVMU.PdEdUx3f7fgnh"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92ebd3378b245f81';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, "\/authors\/wu.maixia?__cf_chl_rt_tk=u1n0d1OwO6.kjQI5zP6Q2b.E2uX4vh1xBB3MulOKAXA-1744388570-1.0.1.1-_JiaNHYi4u7Y_XONdAtHw6ubV4Jacp.kT5Q60p5Ugeg" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>