https://en.formulasearchengine.com/w/index.php?action=history&feed=atom&title=Rose_Peltesohn 2026-09-18T03:52:41Z Revision history for this page on the wiki MediaWiki 1.47.0-wmf.7 https://en.formulasearchengine.com/w/index.php?title=Rose_Peltesohn&diff=29955&oldid=prev 2013-10-08T11:23:07Z

<p>Bot: Migrating 2 interwiki links, now provided by <a href="https://en.wikipedia.org/wiki/Wikidata" class="extiw" title="wikipedia:Wikidata">Wikidata</a> on <a href="/w/index.php?title=D:Q1502073&amp;action=edit&amp;redlink=1" class="new" title="D:Q1502073 (page does not exist)">d:Q1502073</a></p> <p><b>New page</b></p><div>In mathematics, an &#039;&#039;&#039;effaceable functor&#039;&#039;&#039; is an [[additive functor]] &#039;&#039;F&#039;&#039; between [[abelian category|abelian categories]] &#039;&#039;C&#039;&#039; and &#039;&#039;D&#039;&#039; for which, for each object &#039;&#039;A&#039;&#039; in &#039;&#039;C&#039;&#039;, there exists a [[monomorphism]] &lt;math&gt;u: A \to M&lt;/math&gt;, for some &#039;&#039;M&#039;&#039;, such that &lt;math&gt;F(u) = 0&lt;/math&gt;. Similarly, a &#039;&#039;&#039;coeffaceable functor&#039;&#039;&#039; is one for which, for each &#039;&#039;A&#039;&#039;, there is an epimorphism into &#039;&#039;A&#039;&#039; that is killed by &#039;&#039;F&#039;&#039;. The notions were introduced in Grothendieck&#039;s [[Tohoku paper]].<br /> <br /> A theorem of Grothendieck says that every effaceble [[Delta-functor|δ-functor]] (i.e., effaceable in each degree) is universal.<br /> <br /> == Further reading ==<br /> *http://math.stackexchange.com/questions/44382/meaning-of-efface-in-effaceable-functor-and-injective-effacement<br /> <br /> == References ==<br /> *{{Hartshorne AG}}<br /> <br /> <br /> <br /> [[Category:Functors]]</div>

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