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: '92da80386b824002',cH: 'Q1SXb_0bvnzGugbqvqOO1bByJETE3FemusmVVxm7RG4-1744206913-1.2.1.1-MTo9679iP3PFv2lhuNZwIRQF98Vv2G3en2jPsEXJbxFefw6aqlncinA4jM3bdyJr',cUPMDTk: "\/?q=rf%3A7271721&__cf_chl_tk=laP4wehiDytY2ogYzjrfRPrDk9TFyHt59n49I0BBINw-1744206913-1.0.1.1-7m19PW8Xi9WaOURy6dB.vuXcozlniZv93B6JfCFW8w4",cFPWv: 'g',cITimeS: '1744206913',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/?q=rf%3A7271721&__cf_chl_f_tk=laP4wehiDytY2ogYzjrfRPrDk9TFyHt59n49I0BBINw-1744206913-1.0.1.1-7m19PW8Xi9WaOURy6dB.vuXcozlniZv93B6JfCFW8w4",md: "AW1zwDZksfMmRhiKDeafjBy.YGSdg7wm..yFHmFVZLo-1744206913-1.2.1.1-9iNgO82h2mznAxdvZwHfvvAznnes9e8DdwZnZCXfnLqaCfXZjYVsmPRjC3AqNSGjhHEM0le.Bt7_cWT6F3YwANJrehcZYHnvJSLh8D6rKYAtPkTH9wqiQBw.IXR56VBjZOE0mVZbZEReNgFK8zSG_xinSqRAZ_Z0au3f4Efu9jizW67rylPaMJ_GBCilaTCqVrhvlobjQtY1iOj0FXgQv5zY0MMU2fmjNd4JDPpVB_Ez97T1zg5tIACnj.S2qtuK_eHYL5wLzLy52aGlrvcQ4dKveU9TrUNXmaLWCHny2vCT9kTWiKcYmyrkLI0Z8LerindDmX7mC31EYEx_u5DgbeONZ6HB_s.snhY3IALvUH__3hjquu.NcDemw0.6RCb1Ei8TM2FuExNncrgEQ3hYTmeEDjpyUEkJsmT7LP5S6epvb1CYSPhyt3A5bJcNyw48IyfzOXqbaHMlSRvF6jK3IXW0jAQgB_D8Fnclaebm5lcNhDmEFMUnMucK1WuSrBXqPHD5Oi3nRw8vT.Q4UceDzCK_OfdIlFGHFSdV4UvJe5BhgIZEZXxf8zjf7g6k4l.FHdAkoJ.zoT0rYxbaURSjXk0BR6EM7JGAVYyurSnrSY_UJTJmjwSG33P41mOnevzvS2L0F1tquL3zRj9F145PEZ1TiNdQsKvlaKzXIXmgr6W9uer8AaebSVokgnf8zE8pgCr5eqo2fbAjI0DAS7P6kUiRf9utA0aH1oEPOR68.WL63WeXfsnKsYzDASH1C7p_HJEh2otP3MNmcN4OmOlpN2nsPZfePzYHiiAlkJgY..A.0_D3hUDBwH3NV1rOQQRoRdBHaSeAnWvA72QwMMUMXuRsXy.Y8we7a6XhgENGwIX4K_egvs.PC0btwGGWqAzcu30NGXeGCH8ToURnK62eQNw3GTo0Erl1PC_NF6bS0OtIeVxat7_VW9J8JqaqLBj0aD.Ny4tdioakUQjHKo2WLKHwGZMJ0Z7VuQcXN2UbcLwP2SUX2IDSrAePQRBS0iTJhGUtCHe58SkJAbqybxITNMDZ0M1uYWMRgmCGGSbhuVbuGQABe_LVaKuU5LDNN4YDryvhq5WfkjJ7PD.0BplRTz4F5Jsr59wHsO2ASziwyuk5ShbVdroDEDwPlapfnxdelj4SNeafwFYsmSUlqGjvlfdFo8uFpcTe_1uZjndg.0uwM47JWxzXrgeNlTX6WpNo",mdrd: "Bzx7vXSgZPZAh6Z_1_AHk4fLDcePHhasje1WV4nUuvs-1744206913-1.2.1.1-zjOT58J9lWXUFS7nXg_AJa0FDl89aU9X2ofyZi_g6yz3eBQwcQJeCSJq0uIzdT2LpipjwtSzxR1.M82clL1ePNhtqtcXYocUt26VzUwxkRwYMXr4K7F9nM5Rd5nNhQFZyMUQp8xruD3GXhJ96KWV4cpcOpjXRYEUkPqZ9onl0pMAYZMXNcwIATBVGjA0AvnIQLGfqlCkwotTJz76SYNdJ.PUZkBOy3WfwGn24K05i8HbfMIbnvXFDX4Czl8liQh.JYIiM.k1JH.PtEGlY9mRn2X08oPbWW_5GVd8iCuXx7683fiYsibn11UkzR5sO8JNgx4703kuwCyX50d_zpZEhjKuJ97uniHdNxRVzGg.Q6bjPUot4EdfBEdap_vHUvLFhJsquvtbyeksfJcVRT7BM4xyluxn_tlBCFy0XET0cFEYfZUvrFygvQZVhMxgZcABxYuMLDZ7YNju9H1k4Fw4qNA_h2O4C5cePRIx4W6g.6WVtJBXZFRCSOJhVRqJHVuOVPbyYdo8adxUCknM4YpIrmlp11JDrLxQOKQAXFLLJrfY8JicuUavhP9Fnd5IWelMB0yltGgq4Od3cRqIDGrsFo5T6pZrwdcU.j9J5.wYlJKarJ8asuWgv3QupE0gW5YrL.Vqsuv3N_juAIGknUgCbqF.P05yo7LQzCtVzM.py.XWknfPrIiQuMV3Tpm8v5_VZ4H2BN_vf0AfiSyWVjUI5o4dmbowu42oHUAaZActt3ewp5pfKoxW5aDfodyAeXFsoKkbIUb9zCbQm3w9LsP8AOyv1sVT5shFGoHeHx6Y0iw2oGE.ZNCbC0CPw_M3PW5sZ1NlzGmiReenZpZ00RL2ZRcX2i.dh7EawJrtDKsGmpeMugJrGs4gLGV9SQPUp1Gvthwld_MQcUP78cw0S7eX2gSFjQrLQ_D4d4l_rIR9TM6G__mUExKXmTVjeUjoamD9cguLf.i4nbsXI_xBvRiD.qgjTqO12mKr1UO0w6Vwxha8sv5Podzlshb851M.TtywMXrIUQ9MZj0b8VqVpY9FgnN2jivvqo86LEPxdNdyQc8WszyT5dSt0dW9dpBnVKn86RaeWkcYbZfYOjgrY6t6keZ1T12hEdhUUq1x3PTAnJmMMSkl0_g7BKVorAKynHy.zTfVU144V1WwiYs8RBKlTRDJFrPYNFeDA2KMQTBD8OdAdB.0WPO62Vw4TZVkLhVk29_4WMT88Q4sjLbLZfOP6ByyWQJOKFHkjLjXR8fOmc2bXYsu4sRqw.alXKa_UGGeC8SXsXj30eJlp1LcK72gHapxJcsqZIyRgQD3ZUPWRf2KjBAg.lEj6bjL6.BUQFF9f8.lhJ_0wpyASnqlZ5xqHoGjyxXQL9vtApOKw8pqw4ji2ApseLcsz6XO1APbHkOaJG9ojssB0mPVoE.NlDG5xVJ3Plox07VQLdF7JKKnirKzYvH93b2jBAjKbGO0Ck8COE0VNbZKgwPAGasSqdjSJMN8NxyQCnjvr3UjYoHRRDdZa3N_M8VJmzcZg60pI_9AxIfyrM_6_5ivrK9UuCcK3vCS7g2AZCLm8FHt6KXpgoIoG1DTBWBaZtr.MFnkUY8AATbF1QmTHmklSlpqXG8wGZGvyiRrWY8DuAkSHGtN6XrSprpdWyFVHY0MvXdU43POCY2kTSQjz.0OY3d3ubfieO7cA7DWzji_.Z.ULQnmQ_OycWCntLwHYbGkmKxUEs09wdLFunAApsFTq4rH4kpJ_Tui61Eu2j7CfKddgq1XbdmvuUMNHJOZl4y37Y.kkb61NVSekciC0J0k0XHOBLdA_r6Hh2PPyXFgpdEIUC7VuMRUTs6UiSIcTzuC6JLnrrVBQneQt.BCAdJELaZ5E5HHFQxk9Lj57eUOPu9CDuXIHvkPxXaY_i9b5m2.iUmigHOc.Gl4cl2ZiwN3Sre_Oc865qPjEVlj_icwZGfFVy6k67BosknJfb8bRXR5Q6YwNAmkwKuRWxRKx9eB_Le0Vnyq3tOgnpy0QssBaLJcKTEWJFMG39RcjQKJUXWBEyoh.7R7Rl.TYvyJBvQMLxL_J44qEQ"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/g/orchestrate/chl_page/v1?ray=92da80386b824002';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%3A7271721&__cf_chl_rt_tk=laP4wehiDytY2ogYzjrfRPrDk9TFyHt59n49I0BBINw-1744206913-1.0.1.1-7m19PW8Xi9WaOURy6dB.vuXcozlniZv93B6JfCFW8w4" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>