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: '92d754482864fd63',cH: '8wlkfMQWRqgY6_j0mv4CnbTEo_Qg6hX5D_zBytXWGpM-1744173656-1.2.1.1-BGS_ERfLKF3y3IWP0U.GPDB0RnVJB1.Zn10fa8GLSbJv2U7ubH5db0U.KGjRjDlj',cUPMDTk: "\/1198.74041?__cf_chl_tk=oh9cgvkABdvDWp25ncn5NAObTkWcmwDwILWqlb4ZjzU-1744173656-1.0.1.1-4Vb0FC1NDe1BT_lcNFMaxVAp.cmbn5KVYgJ7fS5_Txo",cFPWv: 'g',cITimeS: '1744173656',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/1198.74041?__cf_chl_f_tk=oh9cgvkABdvDWp25ncn5NAObTkWcmwDwILWqlb4ZjzU-1744173656-1.0.1.1-4Vb0FC1NDe1BT_lcNFMaxVAp.cmbn5KVYgJ7fS5_Txo",md: "8V_KpbxwkMCqrVsN0_T5E8SN8ODX1hZL8blPCY8TDNA-1744173656-1.2.1.1-2m8_nkC0F5dXEKl15A0maKBLiN717qnVhDJ3Wz_8Nb2F5wo5E2hmf1C2YyJfjjpAmQg6x6FTjLLNStaGcW40.4B4w2E9WEJl_qKWi06twcownOMKDgPnAcLfRBGLlEEMaJTOBLlrq7PM4ozPqlBcQ7KCstMJF7qTMFezhzix7exC0eTh6XZNnt9G1kHuc6ew5Jcle3G_WoK16egp0ROQ.uLunAzf0.P.K3yKu7iqMrnduhyr72Wm7DCxU._eGq1kkKjNEsnNlw0dW4v2WLRpOehgKp6_Gap_ww5ZOKENW3Cuz6pWTUzlZolEVpgz_7i5SMTUSyEDJPzWSQploinPZy7H3yEIP9VYf3Ec.ekf7v_tmEkxynIcHEJEsRtBa99v2CbgjkXKlqHGL9Jfp2F0LGJK8PJvHY5U7zwhtpcdZ0IyCw_TJXl0FPDl0NAwWKk5iU4xkKkPV.qhCa24rx5B._SESZTx61UeVteNuRsW5tMiD5q2m1yBkzqRcyP9KII367SY68tNKgegYiWZSy_7MC4zufi0evhaHs_BtVhzjMQXwPRf41KfI5R94fi26oQf3AWZ7hyFNWS0l1ptgYFiyJadGfouV9vVK4gmt6aBBwSUuZeU.fsbrJeNWNiXgzMzjIhx6.nLaIjkctj6cRmKJmkZdjabM8kkmWBGlOWiBedWdguJDKQiu6eOFdGDukVx63y0GWCV6lYuC4VEwBlJPC8On6rnyvnKcWF4qeK7rodMpdCsCK9hIujOuyX5Hj9YYZT3O9iZLr_ziJJrL6qDtuTQ4LroyOTIccCUQTLUqH5wxZz8m36tZdDNGttLpF0ejJyzzOUwmcnyPW.AeI2i23KAmuEi_EeEioOSI43xMsVJ37bd47lMlt6OP4g1oUqVn5CGoCqZoom4FsqcZNLRQNsbWC7dwIkEyz4XJ08lCS7LHPaSf4fLrNMz_gUzNUtbwud99yfFg9TrBA46X59AQB9tbRzCuG3FUBam1Ni1wd1f5GLPEPcIaC9r5xTcyhPlNMrwqywGYvSgfkagnCZlVt6M0Be3rNEXR9oaR_Jqh.sKQhVyzZrVuwcU6ofmOhBLQJild_IsKNxJ4PWXJrW91jrORE6bCVOzd46q1NSNStShj3ikfMzlcAVWJTQNPy0yS7Xb2gQqrSZ75lZItbp1dt9lmKqH8G3fiEc6Viy6PFBSKGkpfW1kykSS1brcnUYf",mdrd: "j31M0RV_tMAF.tFk.SA3HX1hQRRaF7IG8ugMy3o5AFY-1744173656-1.2.1.1-FYsSKtLnMtv.RgeBRzgMPBdD4q0G7L4Q1vr.9RbBQpsM2t.z8TQuxYde_pib4DLY76GtcQ.vAOvzMRV0aNMvhxS3ajy2OculxIldZMIzBKelnYyWd_oITCj.M47NYIHjG20Y2PKfPmw96.rwC3RKpJkBwJdC4PCGwbgM9XKWLxDyLJwnOWxZu4rIeh3gfsLwHl1LTrVvOKxMDI1lTW_zG.l0RpKTixeAPQcmNTEZ8AXXZ4zNIAZKqVa3U4QDd3n4eKHd5giZg5S9KPysZOk.BfaT4Lb_.mOnX7VCtyRMAXWxUPOqFNTMJLKSVTHVkXOqUEc2BMBA7xQAFKbx67hY9YXMbN6_3AyV15DXf_.fU8mCfZuQv5QOMMiZE7zJEvgTAZMRAonKEtaROVMB4YwlGhBifcMfQHTAXBUFMrnFWw7xXoDcUFrI5qrvKpojlfBtYjTZLUBohhbinHVZli3Em2js4W2BqAp1upxDJp42QmDQfO8kzQ40ctBoXxU.ktWmeZ80fJ9lo01vlC6gUiZw39s9qzOQY.yPsVKV4F2oh7QhZcgEc3gkjhIWML0UxEGXt4D37KmJrS7F7ObGMXLfhsohYdgPFcodkvRDcNdJQ4r5sF8u9I5NYWDEK4OlIP5VmdB.ECyXRJ.taAz4cfQ8xtgA9zme50D4Rw3T1tZCKUu5QnK_qTdcaZyq4gJfs4ypo4GcA7BDd9HLbmdn63.JIQ7pmGH703V4ePkU426L.ZHFMC3ErNaUhO8ulZrK19ev1xJIgpRKl7NDT_RN4UehHGrvCTb4ydsu8ioIa9GfvB5nq6X98W8VEv7P7QwjQhZLGaDfQJlm5VB384mQjUeGIoKEyW.110Z9wVq0hEIf0I6lQYP6TBxEeQLBKn5jjMeDnQzw7tarZSudaorPvVJEYD3Fte_bIVvV_iseNqLrhqo47Lf9oD5yw9sjpSASg6iaKCwpL6WqCVipe40b1dsz50ih6ujdn.ihJrXbHEJzH_Iddzi_VmQx_hmyP_YNFO4TeJSErlByVSFQYtzTIse2yOp2_hLmSroUpumBf3aaE_qC852SRSPr.tC77GWXq0WDf5ESpN_81LuM60aajgIHdnSAVflbQB8mQ4kMHqa8i_PmTFxlARsz9n3YVTfuShOs.vGrIclFdxwNfgaaII2l1aDxfxo3N4X63fYORmSZqmiFmsMTSTpuOo0x2fWsD_LE.18kzLdNCCJzfE2bNwxFhrZ64rcGPOqtyB_5en6ykMKPR9BkUe0TcGtGnP2eQ5w3ApBdkrwzd_CKN9VlUIiTPEMPPJnCIAniOWAbW2Ek6cDABmZQVY5w1osNC1tudRCZk5gh4ezSewO3t3QjtV9.VurU2bs9lutay3NqCusNKQ.lp2_sg0.XMcLippjrypBHyYAXKr1uOAeBNspbXwhSOLAHu4J9xsoqgHJVZ6uZ8JxWMQGUCsXSaHctEolakFXk4CUFULcxtLwmNCJjBPYLSPavEbXnCSyEcjuPVgoSFgbnmUWVTrv32tlgosi60n0RCYrzpnW8sxikkA8OnTibKVt2GsG3h.7QLcsk0mLhp92x6j8gjtOLnswGxK80lLApNTa6TwV7A_gcg4_5t7PULj8Bvjx_OwTJLshAsczRPQ6Lln3F3eEjumI0N0jaiRgcB2Khofdj6PBE_ikjCNtyU3H_QFkMgwDMIWBfWY_OP5pMRAWrtz92rjaYYO.h2eM8tgTGXferMMIyWxipOI5.6FSzPvnjvzMWEsaK0MOTkqy6t76r8P8OfvHNebfRFHybpaqKM5ox3kavHlLPnhrcj12aJs.zDq.6pAHjz.I.fvCriOMKBtOOyKzZ6B37sQcVw8Mpbb7yIJUQoDrdqwYmOhGOtRi7UptT9hnI1cWtDy2Nt7kOXha2ag.rXHUGCNDdgNoBEX3zJ7YO155jl9wRtYkjq7PI51uZ9FOW3PxXg3CnLfQ9xKr4_JoJVQEa3.VM1wnY3WR.ZkmfWeeI1naJZ3pd.FFO3ofXUh5UI_RWHma_wfoRvrfXC0A5SOxXeWUqpUTe0HRw0dnP2.5TzwUQttzcni6gyEoSY2TLDlL0y6g"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/g/orchestrate/chl_page/v1?ray=92d754482864fd63';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, "\/1198.74041?__cf_chl_rt_tk=oh9cgvkABdvDWp25ncn5NAObTkWcmwDwILWqlb4ZjzU-1744173656-1.0.1.1-4Vb0FC1NDe1BT_lcNFMaxVAp.cmbn5KVYgJ7fS5_Txo" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>