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: '92e8ee81d8d53e4e',cH: '2OFjcfIzlErlBHlxsLq6VtnS5E3Wvxfj_2niR2Hkb8I-1744358231-1.2.1.1-b3nainlC2Rak_xxKzHr_sBthq_JvPVspr4w_DwhM9A_80G7bXKzACEk_pmDN_.s2',cUPMDTk: "\/?q=rf%3A5818797&__cf_chl_tk=Amw.JokVpW0ngteUPOZmbRPOtIe5_B1ZmJ4fIMQdKDs-1744358231-1.0.1.1-EuqljFh_4yK5b6PKmDKzB8a03BY2TEcYf9WmjiC1NFI",cFPWv: 'b',cITimeS: '1744358231',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/?q=rf%3A5818797&__cf_chl_f_tk=Amw.JokVpW0ngteUPOZmbRPOtIe5_B1ZmJ4fIMQdKDs-1744358231-1.0.1.1-EuqljFh_4yK5b6PKmDKzB8a03BY2TEcYf9WmjiC1NFI",md: "XcnlSJMIn.hyXFqsjzkKvy_.0Y0.dqlvPmR68cVKwWo-1744358231-1.2.1.1-3JYgrceOmAGFxAOJct1RbGWeapTrv6cf7tQbGYkDntOMVDg2zXyaOFvq4ykoDerFwMFGtiycfYzvROuq3oWNBkW.uYPlG2ALZIV8wL.VmwSXxV5Jc74Ry6pErWnaIX9soU.72I7qmeGNZiGl3HlRNJXvfjBKmQSKJ6fjIC9zP_ctnkRfv5yYS.uBuV2XpaEnP6pXpksuhGqfl1RpBZv7NLGOExm3tRbxN0RrFE_RExs_8N1IzttfKxtbk14xYJdovGIGdBgKZ7RdYwrWC6QPOUnX4.22OgQ3GsFqq__rMSLCt4luPtxabh8Hw1o7JOQtkuNPOA5YNaGNLLkWvDhvX.YtQNRjtyKZ_OEWA8rAlgXjeAyXiXuSaY2DNijpADFlXV3GYdFBlVlupnP6JbyauZXi7Cl.jii3q9CBvx6rrZLfkguLWTIjb4aLkvwzr_od5Sozgy_tgfwb5kIp7HW_Shy_MJuv6kdBSl5LbNm2FJ4HTulcMr7ybnYaQWVrHCwcQ9WDfXnA3XjbRcnAHvL_Q6K45stRqALxLX7HoyAFA5YqTIEl244dhGoF76yaTgVYHzAdaAkCVFulmerr59OjRp_RkIhtC4aMnnQ.nsslEYMDNqYRXfH4YiuZsmV2JAYZvCJW.MuDjOkwZsZehdRg5SjZyMujUVbNgzc5PtHsa8uiH5NBXLzVNWvu4ChapRPGOVImXeJ96dhMPgRuPvb8p7Uj7AWNtSpUxtdxUhTxX_8gnCiUvtytq8Nm9L6WxHIXBYBkDf2Tx6SxvP4b72Xd1pYssWWibVheQdymZSwv5TDLK73qw.503QvF8ZPgo8NRcNw545SCieS282m7Yf6pODaUUqcFM6aSmvZudndlk9CkE8z0j.IsJCgym0MckIz_9ZSLnNv43CATazLR7KouPYKUR6xgT80OXm4Qtn57ys2FafAS7qJLhdaA.pTqRKqnz3ykS8NIToEpSBek3tLXGK1t2OlvkAOX.mgnEOX_J11fMLdkSeaa_qhChzFUjhUbV9s1kmYjkx8Y4.7WRclYwJuc0eP_8lHaVJht9KrWY97v_FVANt2KY_GpQYLer63ygt7R0N81mj8d4u.941Yz45Ny10Da_2rJUz7UC8cFxJjNFoUp2_hE_yFa7O.vufbvcrx5X9qWj7tN.ye4.9nzKQ7z_X6szmIjZtZyKAZDxAgumdNk1jGKRzzq7RN7MQCX",mdrd: "u7yHSDf6pOSQSdtpgnd.mBT_XqXbvuQOxHjJQoTek9k-1744358231-1.2.1.1-Tc5N8wYjQ1ecriFGB1adWESGFmsfqiUWWaaACihvWZ5Hs8CuoTJea1n6cQz3vfMf1416_v9AL9b_VLFG5WiYMVcdwWhoQWh_Se4uqiPHT1cK_JDpZVzOSuSzL1a6qQ8BLflBHosq1B.AQ6VGjOnr7jeDQhG5LftfWFCxpE1PdolhBfZnTlTwQBD_N.H6XsMzHdzgQbnvnqrtz8ZLV7N5Wmfdh1E3cprWFbdtvWLKicL3YqW..Uzrmg8ezDTf6e6Lfu8x68V6MOeMOIOs4YaJBSC7RRx5BvcYQrjkABjGn2UEOajv_BbHODgsjyMPqFjC3kPlMBe_EgJkZ0lUzc1ZKkP88RPbkZt7FAZyy4Waqv3NWtyDNkv1cnGvLyZ3TqHdB0SCgRlHpCwU2tF666ze9Uc37u3LNjwoA4mQCnD1GbXsfHglcpkIhIATEXR4V86ZQK_pJ7KCiCiHiYDNiNIHApFuWTx5lCAnp2aFT7DQKam9quRFdaHXPKnH5uJYr83DdDKUIjUM35hpogcyocbXf8Kjt_GAzjol2A.lUbXut3ioHplEENj2bvOmXw5xo3AICqs2M6zEk_WlGrJywWfz72BEiHLIsOqOa1vWjP3YwDTIfxun5TamceMcq_HCI7hXvsYS8FqLO92KwD.yj7nFKxR5ETJSVElLAJ3xl3HKOkK2vvhIXbMLWmCZ5jme2t9Ywa.AM66XR7r_tP18iy2HI2YJTnJQf7o6NOjj_ZoXR3xqN8OOk8cXSKNRph6.jPNnr3MpQt4Tpbv_BC.Ys1A9aTk8EyrntzUZJjfJIxfJpUaxPIoT.paMfY51pVsbddbTiV6vSwFXqfs3SC14moqjwTEIgyNABS5WbHXDT1vNzWQaaTvBaPzKb64L_BYHDtv9gGBKbBzKnQjpw5fF_5U4bPzS8lqQd_EwLKtGgZcS45Uer.Lnp9mkfEOPgjehRKEp5mx9GAnEfpgS162dk8JpQKQcg5BfhJ9kr3XGkLiz4a8a8rUWuubUidojUmKACanzt40sWT3_zF3A9bFrPxCqdHEptm0GPmGKiK6njpokKXNWONXnbuo.FXPCqGuvpuqDbTzTOf.AKzaONNugN7QH0ERHCMMMSfnEhdPZ6rsQjf8046uVdMxOrCtjQEbGfsTC293f2OTeUn4GQ8ZCaoOQT5UGVLhVUkDOBF0ciQPWI32WBMyy577kZLEpYk5pik22ImWXy9rC.Ltx5nx1BSlw7MpjgSqwRgg5PnrrKYCrgucul3PBtzBWoHudv4dQ0iIU4bRR4Atb2wq26qA9PygqRqtok2XLCKpgebSrYaBAybI2AqNtlSzSX6R8St_ixsKIiKeOr7k7bM7nNKIgZdRg67lDBkQTHJN8LYoEPbXIB5ng2q75eqCLr0P1TMTWQ6TkS9oQFd4uKjgrjeZFASmRv61d4W14vFhXxVAYuDBo9lOsKwUtpyTt397iZYn70z594lrzxUBGXxHCejwJDrPCfRMSUnmL_ZBnNyUbWBytuZexFw9mGyfP4H4RRyV871H4irFzNyCHWvSgv7xWgwkgtuy0Aa0vJl68uN6yIUQBQBYnD.1j6is1u2edPn8ZyUFTwUC5LdekyBqpDFrbMEu6ANIAghHBGlMOVyDd4EwVvqHROqsIssXSiRncxJR4k.tSFdqDCLj7YyUx6t1wU5r32P6YtCij9okAWT3jTUDn.iISQCicsrJ.eqEh4ZDFHIAYdapyEm8gcdYhvr9xTaG99FxYyDtn81XEUYdCrNF0AsV8ngCnXgi2vKUM4jbWQdYptzGnbowHfGl8Kg4N5xPrsQw5m64IREL68zM_6Dronn0xppN5JQM_ixcOZbftPxTqRHHPRwFt.WQf0pDu2C4y4zhVWDoPkcIBVOREA_9t7Z7vulrshWOnJeIr7xeUJ_l8_hwLhVg1QxwnSl9_n..zWon2M4vm3ayyi85aUYRdJQPG.56Uf1Q3V47iJKJ6kKBKi163xYND6_ziJsak4MSgPrrvEZf0EQb2agvVYKsPJy3T_RciOSb3lyu.2P34I1q2No2uxKBLhbr4qzwhEfGKHMYRU_EK46K7O07cfBj0axo"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92e8ee81d8d53e4e';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%3A5818797&__cf_chl_rt_tk=Amw.JokVpW0ngteUPOZmbRPOtIe5_B1ZmJ4fIMQdKDs-1744358231-1.0.1.1-EuqljFh_4yK5b6PKmDKzB8a03BY2TEcYf9WmjiC1NFI" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>