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<div class="ChapSects" ><a href="chap3.html#X78497E777FB3E402" >3 <span class="Heading" >Objects</span ></a>
<div class="ContSect" ><span class="tocline" ><span class="nocss" > </span ><a href="chap3.html#X7E3651DF87064E72" >3.1 <span class="Heading" >Objects: Category and Representations</span ></a>
</span >
<div class="ContSSBlock" >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7E610FA77A49B9EC" >3.1-1 IsHomalgObject</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X79FC4A848517AF55" >3.1-2 IsHomalgStaticObject</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7F1BC3F77949E779" >3.1-3 IsFinitelyPresentedObjectRep</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X79ED26577A1C2E09" >3.1-4 IsStaticFinitelyPresentedObjectOrSubobjectRep</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7B645ADA876153F2" >3.1-5 IsStaticFinitelyPresentedObjectRep</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X837C31E38502E580" >3.1-6 IsStaticFinitelyPresentedSubobjectRep</a></span >
</div ></div >
<div class="ContSect" ><span class="tocline" ><span class="nocss" > </span ><a href="chap3.html#X7BD901538362C36E" >3.2 <span class="Heading" >Objects: Constructors</span ></a>
</span >
<div class="ContSSBlock" >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X810D3BFB7D9FE47E" >3.2-1 Subobject</a></span >
</div ></div >
<div class="ContSect" ><span class="tocline" ><span class="nocss" > </span ><a href="chap3.html#X7B3E8C797D15F0B7" >3.3 <span class="Heading" >Objects: Properties</span ></a>
</span >
<div class="ContSSBlock" >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7CD2A77778432E7B" >3.3-1 IsFree</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7D49FC85781256AB" >3.3-2 IsStablyFree</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7EC041A77E7E46D2" >3.3-3 IsProjective</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X84A8AB217E8F4611" >3.3-4 IsProjectiveOfConstantRank</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7F065FD7822C0A12" >3.3-5 IsInjective</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7FCE608683CCDC6B" >3.3-6 IsInjectiveCogenerator</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X8784F151844F01FA" >3.3-7 FiniteFreeResolutionExists</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7A6A34C283332F60" >3.3-8 IsReflexive</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X86D92DA17DCE22DD" >3.3-9 IsTorsionFree</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7D8F8A0B81EFD22A" >3.3-10 IsArtinian</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X80C6B26284721409" >3.3-11 IsTorsion</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7B894ED27D38E4B5" >3.3-12 IsPure</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X8373421F7E085763" >3.3-13 IsCohenMacaulay</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X83CBA38E81DC4A72" >3.3-14 IsGorenstein</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7E7AEFBE7801F196" >3.3-15 IsKoszul</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7A20E4597A707218" >3.3-16 HasConstantRank</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7CD026F185A5E41E" >3.3-17 ConstructedAsAnIdeal</a></span >
</div ></div >
<div class="ContSect" ><span class="tocline" ><span class="nocss" > </span ><a href="chap3.html#X805B06828294072C" >3.4 <span class="Heading" >Objects: Attributes</span ></a>
</span >
<div class="ContSSBlock" >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7E6C8ED2865B6F35" >3.4-1 TorsionSubobject</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X82BCEE867CBE84E5" >3.4-2 TheMorphismToZero</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X85EFEC127CA408A1" >3.4-3 TheIdentityMorphism</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X8236B1D480ED04CD" >3.4-4 FullSubobject</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X81679BB58541E235" >3.4-5 ZeroSubobject</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7C16CBCC78C56CDC" >3.4-6 EmbeddingInSuperObject</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7ADC5B647C8E6D8C" >3.4-7 SuperObject</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7FB9A7C3785D92DC" >3.4-8 FactorObject</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7A23EAD67E6B85C1" >3.4-9 UnderlyingSubobject</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7FC5F0AF7CF5DC67" >3.4-10 NatTrIdToHomHom_R</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X81889C777A22A5D3" >3.4-11 Annihilator</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X809A7C3882912EFD" >3.4-12 EndomorphismRing</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X85F3D7CF81E85423" >3.4-13 UnitObject</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7E192147807E66DA" >3.4-14 RankOfObject</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X84FDF25D797B874B" >3.4-15 ProjectiveDimension</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X807BA3C583D3F1EB" >3.4-16 DegreeOfTorsionFreeness</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7E32A9FC81E0E101" >3.4-17 Grade</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X816186E587563E3F" >3.4-18 PurityFiltration</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X8021C33D85444081" >3.4-19 CodegreeOfPurity</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X84299BAB807A1E13" >3.4-20 HilbertPolynomial</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7BC36CC67CB09858" >3.4-21 AffineDimension</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X82A1B55879AB1742" >3.4-22 ProjectiveDegree</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X791B772A7E368A88" >3.4-23 ConstantTermOfHilbertPolynomialn</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X7FC735717985B092" >3.4-24 ElementOfGrothendieckGroup</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X81024DAF8695083E" >3.4-25 ChernPolynomial</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X79942F6187DF4434" >3.4-26 ChernCharacter</a></span >
</div ></div >
<div class="ContSect" ><span class="tocline" ><span class="nocss" > </span ><a href="chap3.html#X7B4D450B78A86F8B" >3.5 <span class="Heading" >Objects: Operations and Functions</span ></a>
</span >
<div class="ContSSBlock" >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X87AEDF2985D65DCC" >3.5-1 CurrentResolution</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X81FACFAC828CA2F9" >3.5-2 UnderlyingObject</a></span >
<span class="ContSS" ><br /><span class="nocss" > </span ><a href="chap3.html#X82AE15AF82136AE0" >3.5-3 Saturate</a></span >
</div ></div >
</div >
<h3>3 <span class="Heading" >Objects</span ></h3>
<p><a id="X7E3651DF87064E72" name="X7E3651DF87064E72" ></a></p>
<h4>3.1 <span class="Heading" >Objects: Category and Representations</span ></h4>
<p><a id="X7E610FA77A49B9EC" name="X7E610FA77A49B9EC" ></a></p>
<h5>3.1-1 IsHomalgObject</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsHomalgObject</code >( <var class="Arg" >F</var > )</td ><td class="tdright" >( category )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>This is the super <strong class="pkg" >GAP</strong >-category which will include the <strong class="pkg" >GAP</strong >-categories <code class="func" >IsHomalgStaticObject</code > (<a href="chap3.html#X79FC4A848517AF55" ><span class="RefLink" >3.1-2</span ></a>), <code class="func" >IsHomalgComplex</code > (<a href="chap6.html#X8166F9FD7BFDA207" ><span class="RefLink" >6.1-1</span ></a>), <code class="func" >IsHomalgBicomplex</code > (<a href="chap8.html#X80B7C45A850F4C3E" ><span class="RefLink" >8.1-1</span ></a>), <code class="func" >IsHomalgBigradedObject</code > (<a href="chap9.html#X795C082E83748032" ><span class="RefLink" >9.1-1</span ></a>), and <code class="func" >IsHomalgSpectralSequence</code > (<a href="chap10.html#X795DCCD88630BA47" ><span class="RefLink" >10.1-1</span ></a>). We need this <strong class="pkg" >GAP</strong >-category to be able to build complexes with *objects* being objects of <strong class="pkg" >homalg</strong > categories or again complexes.</p>
<div class="example" ><pre >
DeclareCategory( "IsHomalgObject" ,
IsHomalgObjectOrMorphism and
IsStructureObjectOrObject and
IsAdditiveElementWithZero );
</pre ></div >
<p><a id="X79FC4A848517AF55" name="X79FC4A848517AF55" ></a></p>
<h5>3.1-2 IsHomalgStaticObject</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsHomalgStaticObject</code >( <var class="Arg" >F</var > )</td ><td class="tdright" >( category )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>This is the super <strong class="pkg" >GAP</strong >-category which will include the <strong class="pkg" >GAP</strong >-categories <code class="code" >IsHomalgModule</code >, etc.</p>
<div class="example" ><pre >
DeclareCategory( "IsHomalgStaticObject" ,
IsHomalgStaticObjectOrMorphism and
IsHomalgObject );
</pre ></div >
<p><a id="X7F1BC3F77949E779" name="X7F1BC3F77949E779" ></a></p>
<h5>3.1-3 IsFinitelyPresentedObjectRep</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsFinitelyPresentedObjectRep</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( representation )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>The <strong class="pkg" >GAP</strong > representation of finitley presented <strong class="pkg" >homalg</strong > objects.</p>
<p>(It is a representation of the <strong class="pkg" >GAP</strong > category <code class="func" >IsHomalgObject</code > (<a href="chap3.html#X7E610FA77A49B9EC" ><span class="RefLink" >3.1-1</span ></a>), which is a subrepresentation of the <strong class="pkg" >GAP</strong > representations <code class="code" >IsStructureObjectOrFinitelyPresentedObjectRep</code >.)</p>
<div class="example" ><pre >
DeclareRepresentation( "IsFinitelyPresentedObjectRep" ,
IsHomalgObject and
IsStructureObjectOrFinitelyPresentedObjectRep,
[ ] );
</pre ></div >
<p><a id="X79ED26577A1C2E09" name="X79ED26577A1C2E09" ></a></p>
<h5>3.1-4 IsStaticFinitelyPresentedObjectOrSubobjectRep</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsStaticFinitelyPresentedObjectOrSubobjectRep</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( representation )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>The <strong class="pkg" >GAP</strong > representation of finitley presented <strong class="pkg" >homalg</strong > static objects.</p>
<p>(It is a representation of the <strong class="pkg" >GAP</strong > category <code class="func" >IsHomalgStaticObject</code > (<a href="chap3.html#X79FC4A848517AF55" ><span class="RefLink" >3.1-2</span ></a>).)</p>
<div class="example" ><pre >
DeclareRepresentation( "IsStaticFinitelyPresentedObjectOrSubobjectRep" ,
IsHomalgStaticObject,
[ ] );
</pre ></div >
<p><a id="X7B645ADA876153F2" name="X7B645ADA876153F2" ></a></p>
<h5>3.1-5 IsStaticFinitelyPresentedObjectRep</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsStaticFinitelyPresentedObjectRep</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( representation )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>The <strong class="pkg" >GAP</strong > representation of finitley presented <strong class="pkg" >homalg</strong > static objects.</p>
<p>(It is a representation of the <strong class="pkg" >GAP</strong > category <code class="func" >IsHomalgStaticObject</code > (<a href="chap3.html#X79FC4A848517AF55" ><span class="RefLink" >3.1-2</span ></a>), which is a subrepresentation of the <strong class="pkg" >GAP</strong > representations <code class="code" >IsStaticFinitelyPresentedObjectOrSubobjectRep</code > and <code class="code" >IsFinitelyPresentedObjectRep</code >.)</p>
<div class="example" ><pre >
DeclareRepresentation( "IsStaticFinitelyPresentedObjectRep" ,
IsStaticFinitelyPresentedObjectOrSubobjectRep and
IsFinitelyPresentedObjectRep,
[ ] );
</pre ></div >
<p><a id="X837C31E38502E580" name="X837C31E38502E580" ></a></p>
<h5>3.1-6 IsStaticFinitelyPresentedSubobjectRep</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsStaticFinitelyPresentedSubobjectRep</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( representation )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>The <strong class="pkg" >GAP</strong > representation of finitley presented <strong class="pkg" >homalg</strong > subobjects of static objects.</p>
<p>(It is a representation of the <strong class="pkg" >GAP</strong > category <code class="func" >IsHomalgStaticObject</code > (<a href="chap3.html#X79FC4A848517AF55" ><span class="RefLink" >3.1-2</span ></a>), which is a subrepresentation of the <strong class="pkg" >GAP</strong > representations <code class="code" >IsStaticFinitelyPresentedObjectOrSubobjectRep</code > and <code class="code" >IsFinitelyPresentedObjectRep</code >.)</p>
<div class="example" ><pre >
DeclareRepresentation( "IsStaticFinitelyPresentedSubobjectRep" ,
IsStaticFinitelyPresentedObjectOrSubobjectRep and
IsFinitelyPresentedObjectRep,
[ ] );
</pre ></div >
<p><a id="X7BD901538362C36E" name="X7BD901538362C36E" ></a></p>
<h4>3.2 <span class="Heading" >Objects: Constructors</span ></h4>
<p><a id="X810D3BFB7D9FE47E" name="X810D3BFB7D9FE47E" ></a></p>
<h5>3.2-1 Subobject</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ Subobject</code >( <var class="Arg" >phi</var > )</td ><td class="tdright" >( operation )</td ></tr ></table ></div >
<p>Returns: a <strong class="pkg" >homalg</strong > subobject</p>
<p>A synonym of <code class="func" >ImageSubobject</code > (<a href="chap4.html#X82FB6A4687E778D5" ><span class="RefLink" >4.4-7</span ></a>).</p>
<p><a id="X7B3E8C797D15F0B7" name="X7B3E8C797D15F0B7" ></a></p>
<h4>3.3 <span class="Heading" >Objects: Properties</span ></h4>
<p><a id="X7CD2A77778432E7B" name="X7CD2A77778432E7B" ></a></p>
<h5>3.3-1 IsFree</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsFree</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>Check if the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > is free.</p>
<p><a id="X7D49FC85781256AB" name="X7D49FC85781256AB" ></a></p>
<h5>3.3-2 IsStablyFree</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsStablyFree</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>Check if the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > is stably free.</p>
<p><a id="X7EC041A77E7E46D2" name="X7EC041A77E7E46D2" ></a></p>
<h5>3.3-3 IsProjective</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsProjective</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>Check if the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > is projective.</p>
<p><a id="X84A8AB217E8F4611" name="X84A8AB217E8F4611" ></a></p>
<h5>3.3-4 IsProjectiveOfConstantRank</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsProjectiveOfConstantRank</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>Check if the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > is projective of constant rank.</p>
<p><a id="X7F065FD7822C0A12" name="X7F065FD7822C0A12" ></a></p>
<h5>3.3-5 IsInjective</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsInjective</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>Check if the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > is (marked) injective.</p>
<p><a id="X7FCE608683CCDC6B" name="X7FCE608683CCDC6B" ></a></p>
<h5>3.3-6 IsInjectiveCogenerator</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsInjectiveCogenerator</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>Check if the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > is (marked) an injective cogenerator.</p>
<p><a id="X8784F151844F01FA" name="X8784F151844F01FA" ></a></p>
<h5>3.3-7 FiniteFreeResolutionExists</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ FiniteFreeResolutionExists</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>Check if the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > allows a finite free resolution. <br /> (no method installed)</p>
<p><a id="X7A6A34C283332F60" name="X7A6A34C283332F60" ></a></p>
<h5>3.3-8 IsReflexive</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsReflexive</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>Check if the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > is reflexive.</p>
<p><a id="X86D92DA17DCE22DD" name="X86D92DA17DCE22DD" ></a></p>
<h5>3.3-9 IsTorsionFree</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsTorsionFree</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>Check if the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > is torsion-free.</p>
<p><a id="X7D8F8A0B81EFD22A" name="X7D8F8A0B81EFD22A" ></a></p>
<h5>3.3-10 IsArtinian</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsArtinian</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>Check if the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > is artinian.</p>
<p><a id="X80C6B26284721409" name="X80C6B26284721409" ></a></p>
<h5>3.3-11 IsTorsion</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsTorsion</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>Check if the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > is torsion.</p>
<p><a id="X7B894ED27D38E4B5" name="X7B894ED27D38E4B5" ></a></p>
<h5>3.3-12 IsPure</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsPure</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>Check if the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > is pure.</p>
<p><a id="X8373421F7E085763" name="X8373421F7E085763" ></a></p>
<h5>3.3-13 IsCohenMacaulay</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsCohenMacaulay</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>Check if the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > is Cohen-Macaulay (depends on the specific Abelian category).</p>
<p><a id="X83CBA38E81DC4A72" name="X83CBA38E81DC4A72" ></a></p>
<h5>3.3-14 IsGorenstein</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsGorenstein</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>Check if the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > is Gorenstein (depends on the specific Abelian category).</p>
<p><a id="X7E7AEFBE7801F196" name="X7E7AEFBE7801F196" ></a></p>
<h5>3.3-15 IsKoszul</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ IsKoszul</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>Check if the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > is Koszul (depends on the specific Abelian category).</p>
<p><a id="X7A20E4597A707218" name="X7A20E4597A707218" ></a></p>
<h5>3.3-16 HasConstantRank</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ HasConstantRank</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>Check if the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > has constant rank. <br /> (no method installed)</p>
<p><a id="X7CD026F185A5E41E" name="X7CD026F185A5E41E" ></a></p>
<h5>3.3-17 ConstructedAsAnIdeal</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ ConstructedAsAnIdeal</code >( <var class="Arg" >J</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: <code class="code" >true</code > or <code class="code" >false</code ></p>
<p>Check if the <strong class="pkg" >homalg</strong > subobject <var class="Arg" >J</var > was constructed as an ideal. <br /> (no method installed)</p>
<p><a id="X805B06828294072C" name="X805B06828294072C" ></a></p>
<h4>3.4 <span class="Heading" >Objects: Attributes</span ></h4>
<p><a id="X7E6C8ED2865B6F35" name="X7E6C8ED2865B6F35" ></a></p>
<h5>3.4-1 TorsionSubobject</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ TorsionSubobject</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a <strong class="pkg" >homalg</strong > subobject</p>
<p>This constructor returns the finitely generated torsion subobject of the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var >.</p>
<p><a id="X82BCEE867CBE84E5" name="X82BCEE867CBE84E5" ></a></p>
<h5>3.4-2 TheMorphismToZero</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ TheMorphismToZero</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a <strong class="pkg" >homalg</strong > map </p>
<p>The zero morphism from the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > to zero.</p>
<p><a id="X85EFEC127CA408A1" name="X85EFEC127CA408A1" ></a></p>
<h5>3.4-3 TheIdentityMorphism</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ TheIdentityMorphism</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a <strong class="pkg" >homalg</strong > map </p>
<p>The identity automorphism of the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var >.</p>
<p><a id="X8236B1D480ED04CD" name="X8236B1D480ED04CD" ></a></p>
<h5>3.4-4 FullSubobject</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ FullSubobject</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a <strong class="pkg" >homalg</strong > subobject</p>
<p>The <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > as a subobject of itself.</p>
<p><a id="X81679BB58541E235" name="X81679BB58541E235" ></a></p>
<h5>3.4-5 ZeroSubobject</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ ZeroSubobject</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a <strong class="pkg" >homalg</strong > subobject</p>
<p>The zero subobject of the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var >.</p>
<p><a id="X7C16CBCC78C56CDC" name="X7C16CBCC78C56CDC" ></a></p>
<h5>3.4-6 EmbeddingInSuperObject</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ EmbeddingInSuperObject</code >( <var class="Arg" >N</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a <strong class="pkg" >homalg</strong > map </p>
<p>In case <var class="Arg" >N</var > was defined as a subobject of some object <span class="SimpleMath" >L</span > the embedding of <var class="Arg" >N</var > in <span class="SimpleMath" >L</span > is returned.</p>
<p><a id="X7ADC5B647C8E6D8C" name="X7ADC5B647C8E6D8C" ></a></p>
<h5>3.4-7 SuperObject</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ SuperObject</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a <strong class="pkg" >homalg</strong > object </p>
<p>In case <var class="Arg" >M</var > was defined as a subobject of some object <span class="SimpleMath" >L</span > the super object <span class="SimpleMath" >L</span > is returned.</p>
<p><a id="X7FB9A7C3785D92DC" name="X7FB9A7C3785D92DC" ></a></p>
<h5>3.4-8 FactorObject</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ FactorObject</code >( <var class="Arg" >N</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a <strong class="pkg" >homalg</strong > object </p>
<p>In case <var class="Arg" >N</var > was defined as a subobject of some object <span class="SimpleMath" >L</span > the factor object <span class="SimpleMath" >L/</span ><var class="Arg" >N</var > is returned.</p>
<p><a id="X7A23EAD67E6B85C1" name="X7A23EAD67E6B85C1" ></a></p>
<h5>3.4-9 UnderlyingSubobject</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ UnderlyingSubobject</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a <strong class="pkg" >homalg</strong > subobject</p>
<p>In case <var class="Arg" >M</var > was defined as the object underlying a subobject <span class="SimpleMath" >L</span > then <span class="SimpleMath" >L</span > is returned. <br /> (no method installed)</p>
<p><a id="X7FC5F0AF7CF5DC67" name="X7FC5F0AF7CF5DC67" ></a></p>
<h5>3.4-10 NatTrIdToHomHom_R</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ NatTrIdToHomHom_R</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a <strong class="pkg" >homalg</strong > morphism</p>
<p>The natural evaluation morphism from the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var > to its double dual <code class="code" >HomHom</code ><span class="SimpleMath" >(</span ><var class="Arg" >M</var ><span class="SimpleMath" >)</span >.</p>
<p><a id="X81889C777A22A5D3" name="X81889C777A22A5D3" ></a></p>
<h5>3.4-11 Annihilator</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ Annihilator</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a <strong class="pkg" >homalg</strong > subobject</p>
<p>The annihilator of the object <var class="Arg" >M</var > as a subobject of the structure object .</p>
<p><a id="X809A7C3882912EFD" name="X809A7C3882912EFD" ></a></p>
<h5>3.4-12 EndomorphismRing</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ EndomorphismRing</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a <strong class="pkg" >homalg</strong > object </p>
<p>The endomorphism ring of the object <var class="Arg" >M</var >.</p>
<p><a id="X85F3D7CF81E85423" name="X85F3D7CF81E85423" ></a></p>
<h5>3.4-13 UnitObject</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ UnitObject</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: a Chern character</p>
<p><var class="Arg" >M</var > is a <strong class="pkg" >homalg</strong > object .</p>
<p><a id="X7E192147807E66DA" name="X7E192147807E66DA" ></a></p>
<h5>3.4-14 RankOfObject</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ RankOfObject</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a nonnegative integer</p>
<p>The projective rank of the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var >.</p>
<p><a id="X84FDF25D797B874B" name="X84FDF25D797B874B" ></a></p>
<h5>3.4-15 ProjectiveDimension</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ ProjectiveDimension</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a nonnegative integer</p>
<p>The projective dimension of the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var >.</p>
<p><a id="X807BA3C583D3F1EB" name="X807BA3C583D3F1EB" ></a></p>
<h5>3.4-16 DegreeOfTorsionFreeness</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ DegreeOfTorsionFreeness</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a nonnegative integer of infinity</p>
<p>Auslander's degree of torsion-freeness of the homalg object M . It is set to infinity only for M =0 .
<p><a id="X7E32A9FC81E0E101" name="X7E32A9FC81E0E101" ></a></p>
<h5>3.4-17 Grade</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ Grade</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a nonnegative integer of infinity</p>
<p>The grade of the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var >. It is set to infinity if <var class="Arg" >M</var ><span class="SimpleMath" >=0</span >. Another name for this operation is <code class="code" >Depth</code >.</p>
<p><a id="X816186E587563E3F" name="X816186E587563E3F" ></a></p>
<h5>3.4-18 PurityFiltration</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ PurityFiltration</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a <strong class="pkg" >homalg</strong > filtration</p>
<p>The purity filtration of the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var >.</p>
<p><a id="X8021C33D85444081" name="X8021C33D85444081" ></a></p>
<h5>3.4-19 CodegreeOfPurity</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ CodegreeOfPurity</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a list of nonnegative integers</p>
<p>The codegree of purity of the <strong class="pkg" >homalg</strong > object <var class="Arg" >M</var >.</p>
<p><a id="X84299BAB807A1E13" name="X84299BAB807A1E13" ></a></p>
<h5>3.4-20 HilbertPolynomial</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ HilbertPolynomial</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a univariate polynomial with rational coefficients</p>
<p><var class="Arg" >M</var > is a <strong class="pkg" >homalg</strong > object .</p>
<p><a id="X7BC36CC67CB09858" name="X7BC36CC67CB09858" ></a></p>
<h5>3.4-21 AffineDimension</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ AffineDimension</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a nonnegative integer</p>
<p><var class="Arg" >M</var > is a <strong class="pkg" >homalg</strong > object .</p>
<p><a id="X82A1B55879AB1742" name="X82A1B55879AB1742" ></a></p>
<h5>3.4-22 ProjectiveDegree</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ ProjectiveDegree</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a nonnegative integer</p>
<p><var class="Arg" >M</var > is a <strong class="pkg" >homalg</strong > object .</p>
<p><a id="X791B772A7E368A88" name="X791B772A7E368A88" ></a></p>
<h5>3.4-23 ConstantTermOfHilbertPolynomialn</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ ConstantTermOfHilbertPolynomialn</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: an integer</p>
<p><var class="Arg" >M</var > is a <strong class="pkg" >homalg</strong > object .</p>
<p><a id="X7FC735717985B092" name="X7FC735717985B092" ></a></p>
<h5>3.4-24 ElementOfGrothendieckGroup</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ ElementOfGrothendieckGroup</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: an element of the Grothendieck group of a projective space</p>
<p><var class="Arg" >M</var > is a <strong class="pkg" >homalg</strong > object .</p>
<p><a id="X81024DAF8695083E" name="X81024DAF8695083E" ></a></p>
<h5>3.4-25 ChernPolynomial</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ ChernPolynomial</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: a Chern polynomial with rank</p>
<p><var class="Arg" >M</var > is a <strong class="pkg" >homalg</strong > object .</p>
<p><a id="X79942F6187DF4434" name="X79942F6187DF4434" ></a></p>
<h5>3.4-26 ChernCharacter</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ ChernCharacter</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( property )</td ></tr ></table ></div >
<p>Returns: a Chern character</p>
<p><var class="Arg" >M</var > is a <strong class="pkg" >homalg</strong > object .</p>
<p><a id="X7B4D450B78A86F8B" name="X7B4D450B78A86F8B" ></a></p>
<h4>3.5 <span class="Heading" >Objects: Operations and Functions</span ></h4>
<p><a id="X87AEDF2985D65DCC" name="X87AEDF2985D65DCC" ></a></p>
<h5>3.5-1 CurrentResolution</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ CurrentResolution</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( attribute )</td ></tr ></table ></div >
<p>Returns: a <strong class="pkg" >homalg</strong > complex</p>
<p>The computed (part of a) resolution of the static object <var class="Arg" >M</var >.</p>
<p><a id="X81FACFAC828CA2F9" name="X81FACFAC828CA2F9" ></a></p>
<h5>3.5-2 UnderlyingObject</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ UnderlyingObject</code >( <var class="Arg" >M</var > )</td ><td class="tdright" >( operation )</td ></tr ></table ></div >
<p>Returns: a <strong class="pkg" >homalg</strong > object </p>
<p>In case <var class="Arg" >M</var > was defined as a subobject of some object <span class="SimpleMath" >L</span > the object underlying the subobject <span class="SimpleMath" >M</span > is returned.</p>
<p><a id="X82AE15AF82136AE0" name="X82AE15AF82136AE0" ></a></p>
<h5>3.5-3 Saturate</h5>
<div class="func" ><table class="func" width="100%" ><tr ><td class="tdleft" ><code class="func" >‣ Saturate</code >( <var class="Arg" >K</var >, <var class="Arg" >J</var > )</td ><td class="tdright" >( operation )</td ></tr ></table ></div >
<p>Returns: a <strong class="pkg" >homalg</strong > ideal</p>
<p>Compute the saturation ideal <span class="SimpleMath" ><var class="Arg" >K</var >:<var class="Arg" >J</var >^∞</span > of the ideals <var class="Arg" >K</var > and <var class="Arg" >J</var >.</p>
<div class="example" ><pre >
<span class="GAPprompt" >gap></span > <span class="GAPinput" >zz := HomalgRingOfIntegers( );</span >
Z
<span class="GAPprompt" >gap></span > <span class="GAPinput" >Display( zz );</span >
<An internal ring>
<span class="GAPprompt" >gap></span > <span class="GAPinput" >m := LeftSubmodule( "2" , zz );</span >
<A principal (left) ideal given by a cyclic generator>
<span class="GAPprompt" >gap></span > <span class="GAPinput" >Display( m );</span >
[ [ 2 ] ]
A (left) ideal generated by the entry of the above matrix
<span class="GAPprompt" >gap></span > <span class="GAPinput" >J := LeftSubmodule( "3" , zz );</span >
<A principal (left) ideal given by a cyclic generator>
<span class="GAPprompt" >gap></span > <span class="GAPinput" >Display( J );</span >
[ [ 3 ] ]
A (left) ideal generated by the entry of the above matrix
<span class="GAPprompt" >gap></span > <span class="GAPinput" >I := Intersect( J, m^3 );</span >
<A principal (left) ideal given by a cyclic generator>
<span class="GAPprompt" >gap></span > <span class="GAPinput" >Display( I );</span >
[ [ 24 ] ]
A (left) ideal generated by the entry of the above matrix
<span class="GAPprompt" >gap></span > <span class="GAPinput" >Im := SubobjectQuotient( I, m );</span >
<A principal (left) ideal of rank 1 on a free generator>
<span class="GAPprompt" >gap></span > <span class="GAPinput" >Display( Im );</span >
[ [ 12 ] ]
A (left) ideal generated by the entry of the above matrix
<span class="GAPprompt" >gap></span > <span class="GAPinput" >I_m := Saturate( I, m );</span >
<A principal (left) ideal of rank 1 on a free generator>
<span class="GAPprompt" >gap></span > <span class="GAPinput" >Display( I_m );</span >
[ [ 3 ] ]
A (left) ideal generated by the entry of the above matrix
<span class="GAPprompt" >gap></span > <span class="GAPinput" >I_m = J;</span >
true
</pre ></div >
<div class="example" ><pre >
InstallMethod( Saturate,
"for homalg subobjects of static objects" ,
[ IsStaticFinitelyPresentedSubobjectRep, IsStaticFinitelyPresentedSubobjectRep ],
function( K, J )
local quotient_last, quotient;
quotient_last := SubobjectQuotient( K, J );
quotient := SubobjectQuotient( quotient_last, J );
while not IsSubset( quotient_last, quotient ) do
quotient_last := quotient;
quotient := SubobjectQuotient( quotient_last, J );
od;
return quotient_last;
end );
InstallMethod( \-, ## a geometrically motivated definition
"for homalg subobjects of static objects" ,
[ IsStaticFinitelyPresentedSubobjectRep, IsStaticFinitelyPresentedSubobjectRep ],
function( K, J )
return Saturate( K, J );
end );
</pre ></div >
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