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: '92e410e109333da4',cH: '8r63f_WLur58f6hYwaKzgyn4PL4jWAYlKjZxjqHV7qI-1744307210-1.2.1.1-9vejc16PEMhIkud4nNDoB2yUUf2fvD2iwYe7EJPl4dOr3lBD228UlYMicwZHTYZw',cUPMDTk: "\/1388.90037?__cf_chl_tk=5GCpiMjSlKXI3CG3bxzmQooLMjVAdI3nLinqb4GfIVk-1744307210-1.0.1.1-gVaTofV4GaLbgV.saZxoxEs07przdCKKuVF8.4xSApo",cFPWv: 'b',cITimeS: '1744307210',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/1388.90037?__cf_chl_f_tk=5GCpiMjSlKXI3CG3bxzmQooLMjVAdI3nLinqb4GfIVk-1744307210-1.0.1.1-gVaTofV4GaLbgV.saZxoxEs07przdCKKuVF8.4xSApo",md: "GTTG0_7XTQyyWF4UamHO4inXxmMZV46IOlNRm8s5gAk-1744307210-1.2.1.1-fqufvhV8pFFXEbe2OJ1d5Wesy8Nnrqs5BC2Pi6G8yz_dWkCiIrlX1TwlYJbm7_N7TrkMunTigPwQtCEUYrz1ZQs3OtC6fwyzgOV1P_bjayeWgCBMN63OGoyT6czmsh7wBTtInQuneoepOfwVwE7BBVUyp4EifXZa1dyFLPRvznrafBhxOgiMQGx.yTYiTZ4u1miM2icxLYr_bKkKsjsnrcWqxO6LyugcjTUr6TVoYbwtEw8iI8GYKU0Qt0HvAXr9_Y7SJgVDG0PVB87518MiRcULrSUfIY5CqdoNZkgVGScomd7S2OvUWIky0epoC_tjpkhjNGTpXRpr14NpXgCIXoozz35oyNaUVp84D1NvLP2fj0rKqocixyYAjJRzGLhai8ny4sU3kqQLljA1CPODUWBkTCapA1UCTRFToq6ethkMv0FVU2Q.ViB.egVkz5ArNXL4ITak80sISaAPlkBp5E_YUdrr.JghMhXjFmqICqX9_PP4eSoPM_n8koaSvfGx4xFdRnSdlyV4RhDMRkABSJWvQQ3WeFTmw_11k28nFFDhyJTz45TVkhUizrUT92c83DaW1HKT3TaiOoeI_WsUPwO8dhFQuORNnVemvONsvyQ.DCbYEeYaQur.IFkelvZDl0yrITni84g5fA2ta7yyl97Hq2_Y7NVdpBzPRhLQSOIEnLpD6WIdok9n5L5pCrk856gcwA56uc0DUCmP4SGc4qQyFWarnUqzPEH2JMeA2VYeJnuMPgM2rmQ9xa8uSlEil4Z9W4_nBxDq3k6Fq9CsGpTPKZFa518n33fXVmgij8cFp9M9zqkyo.AKdqtVRloeUj5RdQqoLTP0vXyIehoei_Hx9to45jU_K_RWRnWLBU3_BmPQ7qxxUnPCoLOu1tmkExZgIwZy014bijcGOhoNbhRlrnY41WW6KdID53KQZlxpcQPL8FFZsgKXeBkW4eBQjjsWMradeqJfOKo2HOwYX1JzDbqc7xLvTNK5FgZhwmT2sHByCWyFjEeG8Ni1dhlHB4vCbrHkwKzMTYJ8BasvF3xNgsRdQGoCTeyT_aOf22KtjaNFeLivIuBygaLVnfumageSIQih19JI3XduJlSoNxScQz7AzZD0TXONhnzjf5.mQYYjHNq3MO4xb6qWgW_BNF.DU.S7TbuwCIY2lzDuzkbItB8L3RplwVclTyGpiIQhQbDyBFgiv5bs6Fy5mymz",mdrd: "jC8rROjxJ93wKi4s55HRhqyjWDgNvhH_TA2VWwBqHjI-1744307210-1.2.1.1-3vYFGzDUAqSuiIgEZhuhrYZ2aO_vj_x6.9LqdSyUIIrBnqg59wJB.mGLTK_45ChJ1w3KVw6oV1p0FvrmrMjcOcwYj2IxWLZFF5tf5kk2aUxcKkrw3OPUfw0CiczR50e3YxzDGFv9U6HrcADeSGD3zDV85GIuRUZ.so5x03iWgIMFGFBn3xJLoMkVxplpN_02TyhQBQPx4fF_jLMQwNzkNrLnZjJfBVv4yF_RbN16kZZ_NuD4IGy13Xeu5xhIyZ6BNojYelUqDBqhxlFdgeaKTTbEh26caIyYo7vIim9Z_bA.vwN2Oxk.giFuV7gQJzhVB3S70.kwgouQCQ2dy5sKVogozxgAoPRIYLznf4BozjLNGHbpJWFinQB9M5r1SvSJAhBRl.YWTH5Ds6AcWxdyHRFw5aSaineEtYXCgPi.7Aw0_ZIotNxtAbF2hxOfCmIlXejRGFHjDTj74glP7LcTFGj2UybDFDiZl.ktzIerr.fgsJs4LnIk.Kr.fIRd4dY1L3AlXNSjqpotqef5qbKdUhBjDfcXJwBHUWXHEfYV92T_N3iGhFb8NWJI8JXSuafLksCu0dI5xnda8LIJ72bvXV74MQnEOmxZtd4w7QC4NfZDAwsOhh.THr.EQQk0X5yV2OfGS2UwTGbbiaeRlraiuny8VhetAmmuBLoOGWrAonBsW2EUIe4vcSRNTtBV7_pnRaP.9QSljv0M9KzZzQce_irXcQ9G1SX3Q6B0mmjNlqQR5WExRGU4H_dHANL1YHsPAi7BHNLph4KkYzn68slhhed_7H3bmbezJ3r2RKu9yjxusGi176K3sE15nZHbZvjs2TO1FSLiktl5pwwLHxgRE27hRJHO5pa8QS1gBnWc4TApSQ2vi2Be5gSAGmdv3SGMxC_D_fg1Mblbq1R6zQfaFT0i_f4E3rLjXNxk7Oko48qLZp38f2Bl8tqMjg..nwdFNRoYJ4UMGv88X5egTCPvrFhHGw_a4cfQWaSCRiIXXbBxE81kZMFaL4gpD5NbvbqONqZKtjjUVAISePxYSeaAnzNGKCBAjLylNnx3saS.ql9nOIVg0NlHvnx2D0Ki0hv9jDxHQ_SyC4fNDdZIm99yzKxoEiMwbnNBFq9xoY8yzB819d29_C2et5DqazngiHgDuaMlzviVH36HAj2JgF6.S6ZOrxefsCyzlPy7DNo2KWRzgjY9uZRtRTp2vRY7S0X7K2oW6kpp8xpT3Y_7g0S7jLEBcFNszzYTGjqYDkoKMgYwtMaBF9CQliVVxV.sCpN6YPtJyNeIcpr4m2oMQ6H.wcY_vGF6G_9QrWJ89xwdwT97s.deNEhyWa8sd6eVP9eRSElSo0uUPztGROOIrvIU7j_.UtXP5pYaJk_R_xPEEPu8x5_mhmZE1ftOiRpbjM1cXaOtZ7JfFz8tKkQhEeREbSp26XeiS6sDURf1P0Z_dbce_LAFfQuab0MD.4E7jGoBcjiFeFnGegR.AF2OZxcH.tyFllvP3kKXyhz0sKoTtWqI0Kpoj1d1lRPsNmePY5hjgnphtmkYcRCfItmp3lcjtZHUiO4L25Dziqg1LbxsKvKXe0TumWiy3nBEyvWRHKL7uxTK5sH3yHDX8sdjmGCuFfG2LRb2Ym0F6yiXy7Z0ZA14EAqmpFC1fIFUNLK6lA7SmJuwZgpQUhNKcrnTzPIn4v7Jk0geKapIFqEQEbnrDvCZZyhoJLPOype8bidL215I9huN47VBdOIH7kTbjROp7pBW.Eco7gQ9qIz0tRfxyUtarlTHg7ZhOGiaxJ5Hj16LgUl49S1jGq2_XupqqJz1FnyyJviswCxrzPf1onO8pFl.h3kp1Y5TUbFGj8JXwGXn.qVw_MO0REpukkuntGIQv0iP4BlmY8Ow3j4QA.hN8.QdMntu04UvV4WD9xp.s0fSJaBC0_uOcdByZ7rqtx3rcCfghJCKswbeFAc7LtFnU32vjfURImbQxbUJDBLTl52ENMMCOirYoPk_a5dxGdnNzoK5Pp1dr7Z2FaLuljBkM14ncm5KIYm7z33UEWttw04s"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92e410e109333da4';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, "\/1388.90037?__cf_chl_rt_tk=5GCpiMjSlKXI3CG3bxzmQooLMjVAdI3nLinqb4GfIVk-1744307210-1.0.1.1-gVaTofV4GaLbgV.saZxoxEs07przdCKKuVF8.4xSApo" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>