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: '92e1cee0396e4ccb',cH: 'bBVl0m8vxML.K4O4oyEKvXGAVg41WCiDeb9Xs4nQZLo-1744283535-1.2.1.1-EVcddDwdAsPvQPMRDbYxNn_qlFhBNRUcegDzZ8uZh9FckKhlJ6YAicLmCQCXAmm5',cUPMDTk: "\/1371.94512?__cf_chl_tk=k7qhTYO3OqWSc0X8bSlqi5rrzz6L9J9QN_C45szo4LA-1744283535-1.0.1.1-5eWHenn2dLzZmHvJ6vymllSmeH2R.bMREdlX2xN9xnc",cFPWv: 'b',cITimeS: '1744283535',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/1371.94512?__cf_chl_f_tk=k7qhTYO3OqWSc0X8bSlqi5rrzz6L9J9QN_C45szo4LA-1744283535-1.0.1.1-5eWHenn2dLzZmHvJ6vymllSmeH2R.bMREdlX2xN9xnc",md: "gxTK5atq3zpsUCY.H1I.0QSuE3NeKVU.HPGzOc7DjRY-1744283535-1.2.1.1-rRGJ2YgOPV0lN0Zof7wnypb9VINIlhD.VYMaZyMUWIMabU3hMvrSdh1COKxrxRHvk1dWBGB6ewb39qstZOaVHaz7mqfsNHfAi9qSmXrTeBHSwYwdJJgvAAn7S_NbLuYpCUPSvFsGcXPaosDzzANrGayaeadn1fzYYJ_wYjmj3tOIR1YhIQGcpl1ay.1keWGOcWJUG_HBNRkEiVGhwCFLfJLLma6_yJ6bYTQhkRZhSxOm_qd2yTrlLMxmZGb_4B0gWs58Et6.IP6QIlweyGfoP_fJE.gncvIWB3kCac8gB3aLcR3iVDWgWBWe61V0C58bNY.0d9UzI2GlM.ZYGNCvLfMmbsN1WpRlr1z9Zjbl0fazWt.nSxZw_Jz498bukfdVzTaDqqcvHQM.A0jkMMOWXIzBsNK0nNEglD_FtduruSF4KzjjuRVszozKPZNblGN7LRX_fyWO6JfBOPBh3MQMZr8oy3MqMJPg0SuVqBrNlXR9BjojR7kSaQoeP7Vf65cMf9cHdQDU1YVwhqLnkXgGleCztERkDYj_ZYaTkorX5_CkFZ3dNP3jR64cMU.CbN92GnyzJVPDhmWb5KyQCRsjWCOzkG1Qj2uXhoQbc20N2v8VLxNdbgUjK5FwYs8THSIh79MhGBqeCikLuSb.g0qQo2w8x.l0_ldAcBPgs.GGIK677STiugBQp4D3lhMeVssXOZMNDp6hOgur03w6RdnWJSr4jnnyehdkYRnOQiKnXooP.QzIhq60sUdnpgxtrgMzP1hrJHVGGhHiOyuxyYCvXRh9EN9RxHD32FTVRETkQfS8sOBY7cjtEzGppkl.fv0IGwuqWXWivCUdnNcYBsIgjP0gp1P2SlWFtY4ifgtGGjc_g2R7YpeQ69Y.ikF.g5cEbdQJ4ma_livG38LSgJ0TXZnpTOaOrds3bezZeRDbW54uJ8czBudvEUMJBjQhsRITexEQd2oEu0qeLLdKfRmn3jaKmKGFZC2ic2S_njqehsa7iI8P0nc0wIpuZ4ssn2a7UFqjiEAF9TZVtqdjp.ILOukFMma3d4HRmnPAqygKQAUAgVBuNMT0xdhvrdKN1paR6BQMXcCP38bLLy51o6tm_4Z_GPz8TXqzUPF5197GFie0p5LKxX0u3FcHlmucbSbbipQqMmYkit4wxm03MZoBMTu.XSN43jVR54XHNnjUW20tQiu_BbWGaE8W4lopENKI",mdrd: "1zMJfOuDVkAHXHtCz2m.AfJ_vZRrmVyAC9l7fg4dKmg-1744283535-1.2.1.1-Ex23sSQn83I_rYO9vTWo5USRBKsBihl7ZEeQcegQ3yAYPGLkGAp4.BC3CuJ47IoBcmeRr9lOlCVdrqJYOdO6Q_TtrzvnHpfEqgOeRcliR2IMNp5IWXQWs.XTK2RFam.31bhP1tOBaqgMo.JweQMhbUKfloR6JxfY0WXBaeOrtF1xrahmURxyhEPlHQsNHd92dedzIrnVZ6QyCnjLF8A1vgj3jtxu75j5jDnBUzPhWaa7.7lRmXn8u2VM1n4sWe.grvIYe4Z7GsiEpu8BZMimpC3R1ZznflKik18Zq2lBUHf0CPWczct9kAZD86vxpCix6AOU0xg4pFMZ0QZzLevyMBzmCRJgXkHKw6xjPx3XvOUE7wdKKLZmLTeFRYPRO3jByJofD3xgCQJsFuX8rbF9D6tkWDnTDTW3Wfit7ckgbLCfWD1G0NjglLM3uyaD4rzBY_rc4MOMaE60Rzr44MkApworF.MB3AXQTy6JoeIF43jIkdvbS7ZaF9wNdur4QmzF7xy0byJ6T7HUqkcxJ1wnOrKD_PJYlfgJ7dln2Yvs1viklnERAwTicE5FIPqqm40oU2FkVikjS6Eu7QC.1LeEhczJbun9EEq9cA3lWJ7eUmbfVjl_S7GdBuEbrz0cwVa_GmPXzT1Jf1EOi4mC4LjXuuS4I2j2devj1Yo7ryk3bwRY.rh1hv9Ox3KSgUOVEAtn.R9v6lIGJZHVgV_w1J6ZtVEpfB5FUyYLkk8Q_zyqglurwnOPfabtB1TM25tO_Lj5itCUjklYSheobNu5kYrDDY54qHyWStjfYxRuL6Frq8n_4kAyUIclRmvJUQtCOkTU5wwX0HRxVL01lz0pzTZmztoDosqv7yBdfds1zAaaDAwDTb6b8puxhV21Hc3Q0w9pHdY3ujM7Lo_PDLKkBFbAQ_yBmH974crHoLn5EkzN7px0q2r13PXUt6w21fbJKqAnnvO7xc_ucFvPhq_UKNRGN26.RKi7H0.l86Mp3.gs3qDd2Ng4MDwkA3TQida7Oj4vLlPGrPOISaxNkp1u.8E7Dgr0rC18WEiQGrk5UdQ5p2t95lHS_.QENsrDbhKTXjQt9fz8026ufwJUGI4LKcjtOWwNhZLJ6X_I_v_FAFMnA3z82TBvaUD_vYyMHGAlh1og1.mGvuWdw.F52GNy_W7jN9iqgYdUiTrUeVT85FjpVtwAgkQGx9LRack06xOuKeOP4YfPxeEN6dRD5Fid.9oV2oO3h9D2z2zc0ABHZzmP7n7VRi1rpSQZX5xJSSp.SieiDUS9t7unX0uC42yzmyhICz93UyR329rYUt0hD0HY_FHt8BmNnng1PwKYAh1xi.wflxKxoNxRS.LOlw0eWPeGkcjEMwfQjhrFCHY55PTMZZp5YX4mCa0LE95yV9uFTY3ghLI8L.AoUs.ai8a_.PEIckTpyOfY9eBRD6CFx.vUd25GcscKFd3y1OTuodr8rwKlMoqbyIzbemIFYny820jYFIMFQCvw9pGoP9Im2bW5npWVagyp1CLwxbkZwPClo9AtIqPXCkyiXXCIrx68yQaI6ZSEY_knz3Etm8viFAxyPi59UjFGkLCtEJ96.GEfUX8OXXwv_mh6CPUZ4iqI4hoDHBoo4zVMs4ETn09sICKeQX2DQOEYtAJdo8mrTHA77NPZarvu058Rb7BO_vjuMnsjUBTi_EegEHdZiXZS0wWfb0dh7R3EGBgMidJCI7g0LMd6CD.LQxnk3Vff_a_dVxoqLXRvNYC6YjViMjId.iIUlnz01moXVg54gDEW_1gbr52Rns_oj2QdzivoxRy8pmd.fljrnQOnRIoRAZ3cU2vGlSRBP7P1IWBKJVUkmD0Sb0kfwZgcCn1D62T1iuFYuISkS1uaMGgIN14464HGfo6rmIJctr4JbBYqsl4a9KHM2MNSxkdpXxZbnQfYqL562MaO0Me1vNV5af6uhMkYf5J3EU9RoS7tYMZQQ3.AQn802wZUey11FJPZMHFRI23mqow6JY92zpRO3nvbpO5vvhqHlHVfk7XZrSjiHvkmyywSCvrM"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92e1cee0396e4ccb';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, "\/1371.94512?__cf_chl_rt_tk=k7qhTYO3OqWSc0X8bSlqi5rrzz6L9J9QN_C45szo4LA-1744283535-1.0.1.1-5eWHenn2dLzZmHvJ6vymllSmeH2R.bMREdlX2xN9xnc" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>