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: '92e58859cc2ffd9e',cH: 'qIIeudMyW4iaSOOWlkBO_Zh7jtxv6pUS.w0C7PkItwo-1744322589-1.2.1.1-Mi0k6Bbhuu.Ky8QfGxiVIDkxTizyc0s4MqzLej1gvrh2gUPF3S4.1SlDwdAmE2VU',cUPMDTk: "\/0642.62016?__cf_chl_tk=irOvR1diCpginJAFPcDrkOaQDnwuiIo.yBGdDhSHrUc-1744322589-1.0.1.1-WKkLfD8CboXqs5zY2JN4L1RfRj7stlKYDH4JgbLl1sA",cFPWv: 'b',cITimeS: '1744322589',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/0642.62016?__cf_chl_f_tk=irOvR1diCpginJAFPcDrkOaQDnwuiIo.yBGdDhSHrUc-1744322589-1.0.1.1-WKkLfD8CboXqs5zY2JN4L1RfRj7stlKYDH4JgbLl1sA",md: "vkbYdbWO9CLAiKDltbIuk4DbT5w_9gsK42l1ZbhfBtg-1744322589-1.2.1.1-d.HslDjn.9_IHwYPkieukDmZCnPtuVGJJyony7K9A3r75TwxFvPj2nQ7bTtY6RMmnnI4Wtnv3I981PAPy4d5L5PSnsWO52yv31nU4uznX7YYltQ.tNV4Gg0kNHIsfREvvTir8GPv3Q1ixC7EvsSTCwh.SGAgPKeXRq1Hsm1L66IoEkzFf6TNCFFOE14TPPpTm6n_61oYOGKXhaZ_I0B9Jqt62juUgNkWLCbItLN8v3zqp1mo4DoyIMBGGfD1HwJ_5eUrIMtSU5Cuzx8ItNbK.JBdrK1zVeukMY6YE2RsxPrKUN6v9oebMgwwQl9V7j0LcANnXCrZsAVOP4.GhELI7eyGJR2vM3iiaZugnLk1k.zqE5OMyy.6D2AtkGB5_Cr2FRbC2HyzI2lStmjuJKoT2xdb13KHF98tgA52kor_T_UiVNovCqXyrLiMSRaedC1rQftYPlasOfqiocfY9X7FidogBHWOp21GvHBsmAGFsgLSct1Q5Y2YuHSsHSAjn2ot1sgNoeVe.dE4nb..r2hKY0LKv6as2u8BelGnzYXCGjtdZrQTLtqcnamFImjVb9SRTFnl3JJxnb9d64r0h0gP_4vsw501cSF7SOO1gc8wnuOemxk7d0VFXOD7mJqr1SK6ap31o.hiDm_pXgzMYWwlPfkHCYqmrDBmABjZSfEBdThJuQB3JqLmymfQW_TqP7rCGR0QfcklqnQVozmc08sLEpWxpy9IE9TMnye3sJ86PmagindjwCQAhZnqsLneceMWOnu3JJc_U7cUtsSF3mNYkjMmoZBa4zqlCfw6ifpOvBU7a9ZwBeJEaHs81T4bD6ZLR4bK1pAtME_0s.8bFfSKQ2HM0_z258Nsx6TTgG4kBtXfQ4jAOZl5All2zq1GNhftH1oxG_DELBuZQJKdojcfyWpgJI62KhxClmkfkWthwjKlIFaRNSWGNFk9A2PKcvEAjQUt9i7nSoEWTX0Zx..sY.0Ly1pPOiaysLNyFdFqAH0YfLOpaF1lOtA1uwfiWCAuOBXqWEKnpL4y5YqHCGnD5p13.5mJDVgFWAgMKXp5JXrCnM4uxfF9yIl2rBEOtJ1nqlaL_3F5aL5h_sBIJLcU0QaEw1pzq_ExDbdew4yBQfbKoxAQfzY5KTPv_A27W68T28vn9meyNWY5dVzQcbYtSiE_517kNmwuuLRIwqxyZNLVTroMRbhtbheNs1enwS2n",mdrd: "fTJOm5Nfwo9dYBqyXLhiG_.masJVtE9lQZxOgfNNjrk-1744322589-1.2.1.1-5HnWG0gmvvY9PAhjk1HwBJNExIZdiKuVn7YPpuzogSZztb3XAk5gqjI05u_Z3A6BFsL2RRyB7XZhwoVZT99oqKv8KA_AVPiAujRMd7raY2EXtBextmGu1U8U1DCd9REWaOS19x5vIRUsc1mhI9YbIIK1SetywZIp1gxbzcyJ5PXsUP.EgHhN.lS6ouijmwvh5bLzglAau3kqy2KMc.lB.vElI2sQC3f1K1gi69ltbVuYNH5MTkma6rPFc6kQ0grDFFJyJUt1JG62yHu3l2rW2ne1W4_IOe8RBt4UlHzjsWHN_PTq87cZS0cNBXnSWk4R8hhu1adGpBx4U5QjVAemis4dFHZw1o65_uueHyoj3ryqEZqgpwincHWwhGX.pGfNL59UXtV6y75co1Q1akk1s3DhqKXNuPOjtlJ0LfNSPJGRjAr6vJmebjnanWthu9KGrBwKe9Twb8WDjWXS25V7n1uFXiBA7zqxItWLSTIUSbV_7cLsBxhqj2MT9inYoa0GH16hRdOAxLcCirjkQqqIbHYq8HVfvmMaf_Fs1446dhSx1ieyaioZSxhtAKQvExa_Tih8MmAWDE1L_S_ivS052RbkWqoQQyODfwepe65J1yeE1eye6_nGFB9167uVnwGiETaxquV.wy1bAAlZnga72Kgi2MFJX8cYRedXW2d_091SW8dw5AL7Qw7DnxW3dBu0v50bS7z0oJW.XV4G8Wa.HFWn5zXPhdjTXKgkGEnPI8gtO4OGqKTMgSFKjeyqHAGI5FOR9s2hKMN.maKMpygZR9ydvLRWnlHCBuK_SxMSggheYwFg3F1xt.HQZS_MXVFmYaJ8qgRrZmgUz4cHOwaRzJPpqK.nOSS_Kd9yMs1.PKHn8GfSxnO813.ijavSLSrSaS4BZhovx7OyO8oo0FksryiK3jDWMYWqQT8z6wgmT0pTqksqCqUUShd6tE2kBLxoPZlXVUHMfxZ.MZlMWmNDnLqAXFvUwojKBMdxsXRghoCyk1cPnzxnpGTvlDu6FOX0zHxfX4XZOPpbtHzREAAZRGyzrgnkCWgw3qblxXHoIpoDSRuZveFOqz5tMug2ZTZHRq2T2HWIx6kyXhUsZWBA_slbMO8lP.snFKdnRa0Vsc3o1J6WkHfEr6NrGUharY8cAqW.2PLKrQ_exT3vywTg0GMZoy2dWGLuqGhFFaLorjbaExY6Z2dQbxkkMaAd7qJeXz2FMzn9vYfOeTEUSM2j6L8k9GC_ICBWNZZ5nb5n_1WH7r32ceirGrX_2ju61mBODHlzD5uir53dTbr.J1jOcw4HenfyM_YwIcSFlZPqTcv3szHHKM0.gsTTs1Y7zcMb0s_pLH3okb8YiaRtoiDNDJbi9rIGVUXvKhXpzGXOwmq5S3iHYOdh2uuVtV2ir_mfHulL2rUfOp6002pak1Ga8s8o9.rezS8eLgIa2a.hABDJEucVwoa5HZnvBYcp.RB_Ei7oG7DUh24ksjpLfd8j6hLjcTJ3WnUD2wHa.sgNMFZKk_4bP.5T32oalVqtHsgana8QaSkPo6sYrHZnVxiarmVrBhg9SWu4bNuGf5mNFr2RIUg3xKZh3nFw2wpveOCOjvG7ViUIxYlJbX3OMNl.G7CFCo3uSWn.RSbV5xm0jMAIKPstowjuOyeefSQM8AglFD3Bzv3AmWHebpuYi4CP3pgepehdF3az4Phju8YhK9lo.JooMm_JbDgkbOFjXgZPPDJ9VvokinTVha9EbFA2MTMdgeutUNMV_TdzDMiZgZKFvEXOOFFtHP9hEWdhrNKow4U.PFBFeK_GpBKeFlgPzFvin.iYdOqaK20MM2ABggbJjbG5_Jrno5pDnqz23sRASU7kZaK__KqYipQxfC.GnEvW5sXXBa9HpE0VHArBeEytrO22dqUzFplPTvnSeex6zMos2MBBG6jrg7mS8sh.S1O02TzT_PjsrK8cnKxt3P5vNtux3SXI6kXRHjbOR_0NmuPRLp2fMiePPDJ.7SrNUzys_U7rpgtEEyWGqjRTHofYZRBREsfpCl8I4ZBLMtjx"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92e58859cc2ffd9e';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, "\/0642.62016?__cf_chl_rt_tk=irOvR1diCpginJAFPcDrkOaQDnwuiIo.yBGdDhSHrUc-1744322589-1.0.1.1-WKkLfD8CboXqs5zY2JN4L1RfRj7stlKYDH4JgbLl1sA" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>