CINXE.COM

Just a moment...

<!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: '92e5f5592c5deba0',cH: 'd0Ofs3xZ7hBXtdM5yj3zrhFilrqLMeOzWjNClfsOSAQ-1744327054-1.2.1.1-0ScxSAbRwvJ3GI95l.p0Y255IOxHQhWCQYo0rg_oKR1Nd6GETRCHhxdzvQ1wZ7j1',cUPMDTk: "\/?q=rf%3A7508241&__cf_chl_tk=FrP_A7NuRZn3kG7_uxsVd0iW5WIomsa_0RieEnBX1R8-1744327054-1.0.1.1-s247gL39IwaIBJDzheBIW.KHjjI2L2d7v1ySosjQfnw",cFPWv: 'b',cITimeS: '1744327054',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/?q=rf%3A7508241&__cf_chl_f_tk=FrP_A7NuRZn3kG7_uxsVd0iW5WIomsa_0RieEnBX1R8-1744327054-1.0.1.1-s247gL39IwaIBJDzheBIW.KHjjI2L2d7v1ySosjQfnw",md: "FgU7eBEP0nhhpR2JCByJjMJyu_bSNHyCs35PKFuAIVc-1744327054-1.2.1.1-kJzpwKhj1n3xYS3Kr1CkNfyrfh6xbqPYjmkUq2iXHnnCO3g0yyAR8ePDcIq4BdDRR6eQtdCxtwka.boM4dzKAW9kxFNH17eZG0ajOmqZxmg20QG2_FeiaKMCHeoukMr5dZasFZ5qMikGybzwr4wkeFcoX2YJKLZQlfs0OS10MYwPj2IbNWEFwstAj9syX8oI9CZF0xGxY3bXc6mTYemFstwWsGEcKR4t5isEKaIsmm9fGuPXrbNvPEcoyJAcO3opxGWZoiA79dOy9qCeXOb9mBG53uZ2wlu6MfYVtnP17EwHWJI5L.VzJ2SPm6hOyLxWV_HW_JiIdIeehR8bN9sKBlRT9IUNqvIUCM7Zyz6Vk9wRT03Z2Aen7kU50JtkvpOSIx4qQGimXsR3lX37oYuha6qHMB4HWZGLW7ZteSFwG9X8Edc4Ezbs4XELhwoziZY4CIZBAMII4LmeOkoGAVlQksBclm5FORXIE0BdL2njcIIuF7Er4.j.c9zPMB1WBvck00sA2RRV0KjWjRPkGIGZlSabujAHRHDVVAnIcSR_V1uWnvcsrdlXcfFdeUFTVOLbXP4WryVY.DAA8TaXqxt2IcoEQo_I8maWtl3PUY7G_CfHDZ1u8ty6_Vv0bk7w5TbBpbz6p6i79EDSZRu2sToUK0HaLnc8j6wVJUch0WAJ_KzWnQnGNEVMHC9.DbGhQWLGfix.GBRksD_ZGdLeIIUSHs2N9VJb5j8TOa51QTksuHTHZTZ33pdqMsPxZ4mlhf2FAEggu7grLj0a9XlRMcpRMewJGs8wreZQxpZNPzqAWLGmqGKzLHCH0qHDyOZLM.zvjcDca85KxUUUkuJdeXCM4xtRYfwWpTfuDIpKHAWLTROdP3Tt.LBY8_h.ezmX0y0qG9xXSS32OyRJdJs.mFn.wQbrrJCM0_3G3yCTvjswQTS1tlLuT7YGJ8f88OhOIu2Qldo0pNPEOhRgkn063SaLosItDReR0fm1pSkv6hkdARyeQ9sYtjL0yZzqasPJ.3EnnknCosedlCooMSGt8i9eTVdiLq0jRsFS2jaFMdZfWrihBQH3.yhBg5Voo6wq.dQocBZxtzBHERc1M2i8DEy6gyVzkPfX0ahTbo1zkkir.06fnRT7Mmbay8HzTR2e54PWV7z_PtIzYQTGh7QuqB4BsCGnDPjqXx5ciJAqzhkCfPfUN85yqbXVFvUnlu5_hrdf",mdrd: "1LlX6QaIlKdP53B.QscTnj0gWXv1Xg6moC9x7Rp28t4-1744327054-1.2.1.1-DVeINaISG0t.nt9y_eNAJU_Fu3yvgx4__v5oAKfVy2t_WTfd7KA7d7HfLei5cd0_Y.tq_HxlG4T2JxhYfbZtjnz86.cS5KrSu5I.Ruz_8RsjqnjNNRoUgRMrH92s4YnykQ8IERTAfqtWQhlu4W4BpQ3_yujov4DK5Kf9jBFYDAyvpXbUXQiKCd6ZrsJmOBRHiMoTAsVHmUYPdEb5konbgLOEX3XRFopvua31QI3UKZyzw_xS_xKx7hgikLw75YSb1jeghZYRi4bqEy2djQRz0Hf8BDFZ3nMBfCOT65CN3f9R2oUeTmWU1tEJfXhDdyzxZwSNqin.VRoHZQ6aMLuonLLPt9qblfT_x3isJ_pvNxQ7OWlcjpGAHmYXR1E6wHTn0DyTO76yOyIi3dZfDKIHHP8Y4Bdy9lWQGnsUO1bYTqW90GZjSbutpuYUDKW_cRvimrwvziqbEOffUIN.sQvB4PY_VmCaONhUBwICf2nH0Cxfn_qf2AvTeVOoEfxAWZCaSbEqFWoZE8aTG.wQnOyNZZdZxRIDhxMNEg8rvMNT5YLmOUd2.QDv0ak5gXE8f3fMmENWvrJCHHg5IfjXwh3RH08XVt1rcKWKrOhRULOkvAaut3mVv7iVB7jzj5xTUyYEyYmIEW6DaYiJjlyjOWzw1gDNFS3QXT7iv0tKCI0qcLFiM78ZLGfgu.5x8H0weoUSLgf99Mt03B0cCmWQpJewd_uZQmzfd_pR.nc7uYh0_0qnROHAlKSYHH_x8HvLKzNBF4nfPQux23hkOfNjNLCmUVaxBB7Nt5laWLKqe4HzTnmYamW7MiSh1phznhYuDPt1Q1Um.3dKvfUjAynRaTIym2ZkvhO.yNjqQheHR8LXsaDMqxUueyOXz5zCnjNHuhFUPSeqm7gkZJ4Q5RpYyFX3QYnLzBJrUF4sPxU6vo1xh5QVH0x3QAO7p456ttDVDzkCWoudplB4IDa.FGtGZUjr3K29HtW2QsB95iRkLVk79LBwkWwR6xSLJAiFqCYZ_4JxkkqlBZvalf5aX_WJ47yNpeHBkzXBs.I5qOMZRVZncgh.O_ixQMiimVMxfqKYof4hOImYyqoQpAi1BFh7csy7S5wFdWFkdSRCH3WMbSP9zqtXYSNrTnxDL8GDtzBszUmzDZAwaSLexLsbIKcIIamrRkOVeEZbl7L1YxYT7nEZ_1V_bVTdf20Qy6OjiZc1dPsfIw7geDv7SaERLpiyggiPwWKm4qj49jYC1Vxi.UeJ.QznKxy5tMLhq.Z4Uq0AvTk0Lr.nGXtU7Eg9HuSonWR7oAgVkmX0IicQxhxG1pZb1NNPoQS2n5iejxcb_ZShVKp1Q_4y.gT1NDuDtyYRq_bixqzcw18KYre80RENKQVY_tZNEMLmCVyTIOlX_0Y42jB0S.faNRHGYeUoStutTZy7AgUhFN9hAXGqKiL1XmhBSpCLBBY5o5rAsz4J.ryEf5Q1wWiTl5ze224aLqi0SkIPo.5xdLQ7WU.QVe_3QaqZ1GG8By4GKJ1ROSMB_k7kj7qYezpMztoQIFR07elpoPAH5XnFVf.H07pFhzt9r3x9fs7dWrhMrggvZJQMREpm8wO0_sKwtrww8PZJLYExhq53_UhoCmBnI498J2Dag_8nW5.cMo6n1YhsWetu12TnK2qpzr5xdDZA_ytn9fyMlxlH.ipn6_HTXw9lqvJKyQP9Z8wMYZ8mgGt6lBm91R_Yle2Db98g69GO9At407T7de.tVAgpSznFNjhqkUx1tW9lQk.3VKlFhi4AHBOdIqcgqN6HDi_JrJvDZV6EEwIQyklCuUgsY1iy.ldshfsx6sPjbz4MLzi9RdcR5qOmSHsfUJQ79EHHVuJSA3Gue2lXR9iVRDBQQZc0NokMiPLtMbuBep2Ukiu_C.ODZXgy73MG907AYzJQg3wLOV7SUxvXDelw6WH7GjduVvxBqqOmkd8o02FJT03oq94iGzuckqX36nq8uymhgKJlfbIg5yr4TPpq3xdjyHrzmDWgO4moK7Q6PjjIV16G7yZZAH89sqXyN_b0"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92e5f5592c5deba0';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%3A7508241&__cf_chl_rt_tk=FrP_A7NuRZn3kG7_uxsVd0iW5WIomsa_0RieEnBX1R8-1744327054-1.0.1.1-s247gL39IwaIBJDzheBIW.KHjjI2L2d7v1ySosjQfnw" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>