GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
<Chapter Label="chap:demo"> <Heading>A demo session with <Package>simpcomp</Package></Heading>1This chapter contains the transcript of a demo session with <Package>simpcomp</Package> that is intended to give an insight into what things can be done with this package.<P/>23Of course this only scratches the surface of the functions provided by <Package>simpcomp</Package>. See Chapters <Ref Chap="chap:polyhedralcomplex"/> through <Ref Chap="chap:misc"/> for further functions provided by <Package>simpcomp</Package>.45<Section Label="sec:DemoCreatingCompl">6<Heading>Creating a <C>SCSimplicialComplex</C> object</Heading>78Simplicial complex objects can either be created from a facet list (complex <C>c1</C> below), orbit representatives together with a permutation group (complex <C>c2</C>) or difference cycles (complex <C>c3</C>, see Section <Ref Chap="sec:FromScratch"/>), from a function generating triangulations of standard complexes (complex <C>c4</C>, see Section <Ref Chap="sec:Standard"/>) or from a function constructing infinite series for combinatorial (pseudo)manifolds (complexes <C>c5</C>, <C>c6</C>, <C>c7</C>, see Section <Ref Chap="sec:Series"/> and the function prefix <C>SCSeries...</C>). There are also functions creating new simplicial complexes from old, see Section <Ref Chap="sec:generateFromOld" />, which will be described in the next sections.910<Log>11gap> #first run functionality test on simpcomp12gap> SCRunTest();13+ test simpcomp package, version 2.1.714+ GAP4stones: 6998815true16gap> #all ok17gap> c1:=SCFromFacets([[1,2],[2,3],[3,1]]);18[SimplicialComplex1920Properties known: Dim, Facets, Name, VertexLabels.2122Name="unnamed complex 1"23Dim=12425/SimplicialComplex]26gap> G:=Group([(2,12,11,6,8,3)(4,7,10)(5,9),(1,11,6,4,5,3,10,8,9,7,2,12)]);27Group([ (2,12,11,6,8,3)(4,7,10)(5,9), (1,11,6,4,5,3,10,8,9,7,2,12) ])28gap> StructureDescription(G);29"S4 x S3"30gap> Size(G);3114432gap> c2:=SCFromGenerators(G,[[1,2,3]]);;33gap> c2.IsManifold;34true35gap> SCLibDetermineTopologicalType(c2);36[SimplicialComplex3738Properties known: AutomorphismGroup, AutomorphismGroupSize,39AutomorphismGroupStructure, AutomorphismGroupTransitivity,\4041Boundary, Dim, Faces, Facets, Generators, HasBoundary,42IsManifold, IsPM, Name, TopologicalType, VertexLabels,43Vertices.4445Name="complex from generators under group S4 x S3"46Dim=247AutomorphismGroupSize=14448AutomorphismGroupStructure="S4 x S3"49AutomorphismGroupTransitivity=150HasBoundary=false51IsPM=true52TopologicalType="T^2"5354/SimplicialComplex]55gap> c3:=SCFromDifferenceCycles([[1,1,6],[3,3,2]]);56[SimplicialComplex5758Properties known: Dim, Facets, Name, VertexLabels.5960Name="complex from diffcycles [ [ 1, 1, 6 ], [ 3, 3, 2 ] ]"61Dim=26263/SimplicialComplex]64gap> c4:=SCBdSimplex(2);65[SimplicialComplex6667Properties known: AutomorphismGroup, AutomorphismGroupOrder,68AutomorphismGroupStructure, AutomorphismGroupTransitivity,69Chi, Dim, F, Facets, Generators, HasBounday, Homology,70IsConnected, IsStronglyConnected, Name, TopologicalType,71VertexLabels.7273Name="S^1_3"74Dim=175AutomorphismGroupStructure="S3"76AutomorphismGroupTransitivity=377Chi=078F=[ 3, 3 ]79Homology=[ [ 0, [ ] ], [ 1, [ ] ] ]80IsConnected=true81IsStronglyConnected=true82TopologicalType="S^1"8384/SimplicialComplex]85gap> c5:=SCSeriesCSTSurface(2,16);;86gap> SCLibDetermineTopologicalType(c5);87[SimplicialComplex8889Properties known: Boundary, Dim, Faces, Facets, HasBoundary, IsPM, Name,90TopologicalType, VertexLabels.9192Name="cst surface S_{(2,16)} = { (2:2:12),(6:6:4) }"93Dim=294HasBoundary=false95IsPM=true96TopologicalType="T^2 U T^2"9798/SimplicialComplex]99gap> c6:=SCSeriesD2n(22);;100gap> c6.Homology;101[ [ 0, [ ] ], [ 1, [ ] ], [ 0, [ 2 ] ], [ 0, [ ] ] ]102gap> c6.F;103[ 44, 264, 440, 220 ]104gap> SCSeriesAGL(17);105[ AGL(1,17), [ [ 1, 2, 4, 8, 16 ] ] ]106gap> c7:=SCFromGenerators(last[1],last[2]);;107gap> c7.AutomorphismGroupTransitivity;1082109</Log>110</Section>111112<Section Label="sec:DemoWorkingCompl">113<Heading>Working with a <C>SCSimplicialComplex</C> object</Heading>114As described in Section <Ref Sect="sec:AcessSC" /> there are two several ways of accessing an object of type <C>SCSimplicialComplex</C>. An example for the two equivalent ways is given below. The preference will be given to the object oriented notation in this demo session.115116The code listed below117118<Log>119gap> c:=SCBdSimplex(3);; # create a simplicial complex object120gap> SCFVector(c);121[ 4, 6, 4 ]122gap> SCSkel(c,0);123[ [ 1 ], [ 2 ], [ 3 ], [ 4 ] ]124</Log>125126is equivalent to127128<Log>129gap> c:=SCBdSimplex(3);; # create a simplicial complex object130gap> c.F;131[ 4, 6, 4 ]132gap> c.Skel(0);133[ [ 1 ], [ 2 ], [ 3 ], [ 4 ] ]134</Log>135136</Section>137138<Section Label="sec:DemoPropsCompl">139<Heading>Calculating properties of a <C>SCSimplicialComplex</C> object</Heading>140141<Package>simpcomp</Package> provides a variety of functions for calculating properties of simplicial complexes, see Section <Ref Chap="sec:glprops" />. All these properties are only calculated once and stored in the <C>SCSimplicialComplex</C> object.142<Log>143gap> c1.F;144[ 3, 3 ]145gap> c1.FaceLattice;146[ [ [ 1 ], [ 2 ], [ 3 ] ], [ [ 1, 2 ], [ 1, 3 ], [ 2, 3 ] ] ]147gap> c1.AutomorphismGroup;148S3149gap> c1.Generators;150[ [ [ 1, 2 ], 3 ] ]151gap> c3.Facets;152[ [ 1, 2, 3 ], [ 1, 2, 8 ], [ 1, 3, 6 ], [ 1, 4, 6 ], [ 1, 4, 7 ],153[ 1, 7, 8 ], [ 2, 3, 4 ], [ 2, 4, 7 ], [ 2, 5, 7 ], [ 2, 5, 8 ],154[ 3, 4, 5 ], [ 3, 5, 8 ], [ 3, 6, 8 ], [ 4, 5, 6 ], [ 5, 6, 7 ],155[ 6, 7, 8 ] ]156gap> c3.F;157[ 8, 24, 16 ]158gap> c3.G;159[ 4 ]160gap> c3.H;161[ 5, 11, -1 ]162gap> c3.ASDet;163186624164gap> c3.Chi;1650166gap> c3.Generators;167[ [ [ 1, 2, 3 ], 16 ] ]168gap> c3.HasBoundary;169false170gap> c3.IsConnected;171true172gap> c3.IsCentrallySymmetric;173true174gap> c3.Vertices;175[ 1, 2, 3, 4, 5, 6, 7, 8 ]176gap> c3.ConnectedComponents;177[ [SimplicialComplex178179Properties known: Dim, Facets, Name, VertexLabels.180181Name="Connected component #1 of complex from diffcycles [ [ 1, 1, 6 ], [ \1823, 3, 2 ] ]"183Dim=2184185/SimplicialComplex] ]186gap> c3.UnknownProperty;187#I SCPropertyObject: unhandled property 'UnknownProperty'. Handled properties\188are [ "Equivalent", "IsKStackedSphere", "IsManifold", "IsMovable", "Move",189"Moves", "RMoves", "ReduceAsSubcomplex", "Reduce", "ReduceEx", "Copy",190"Recalc", "ASDet", "AutomorphismGroup", "AutomorphismGroupInternal",191"Boundary", "ConnectedComponents", "Dim", "DualGraph", "Chi", "F",192"FaceLattice", "FaceLatticeEx", "Faces", "FacesEx", "Facets", "FacetsEx",193"FpBetti", "FundamentalGroup", "G", "Generators", "GeneratorsEx", "H",194"HasBoundary", "HasInterior", "Homology", "Incidences", "IncidencesEx",195"Interior", "IsCentrallySymmetric", "IsConnected", "IsEmpty",196"IsEulerianManifold", "IsHomologySphere", "IsInKd", "IsKNeighborly",197"IsOrientable", "IsPM", "IsPure", "IsShellable", "IsStronglyConnected",198"MinimalNonFaces", "MinimalNonFacesEx", "Name", "Neighborliness",199"Orientation", "Skel", "SkelEx", "SpanningTree",200"StronglyConnectedComponents", "Vertices", "VerticesEx",201"BoundaryOperatorMatrix", "HomologyBasis", "HomologyBasisAsSimplices",202"HomologyInternal", "CoboundaryOperatorMatrix", "Cohomology",203"CohomologyBasis", "CohomologyBasisAsSimplices", "CupProduct",204"IntersectionForm", "IntersectionFormParity",205"IntersectionFormDimensionality", "Load", "Save", "ExportPolymake",206"ExportLatexTable", "ExportJavaView", "LabelMax", "LabelMin", "Labels",207"Relabel", "RelabelStandard", "RelabelTransposition", "Rename",208"SortComplex", "UnlabelFace", "AlexanderDual", "CollapseGreedy", "Cone",209"DeletedJoin", "Difference", "HandleAddition", "Intersection",210"IsIsomorphic", "IsSubcomplex", "Isomorphism", "IsomorphismEx", "Join",211"Link", "Links", "Neighbors", "NeighborsEx", "Shelling", "ShellingExt",212"Shellings", "Span", "Star", "Stars", "Suspension", "Union",213"VertexIdentification", "Wedge", "DetermineTopologicalType", "Dim",214"Facets", "VertexLabels", "Name", "Vertices", "IsConnected",215"ConnectedComponents" ].216217fail218</Log>219220</Section>221222<Section Label="sec:DemoNewCompl">223<Heading>Creating new complexes from a <C>SCSimplicialComplex</C> object</Heading>224225As already mentioned, there is the possibility to generate new objects of type <C>SCSimplicialComplex</C> from existing ones using standard constructions. The functions used in this section are described in more detail in Section <Ref Chap="sec:generateFromOld"/>.226<Log>227gap> d:=c3+c3;228[SimplicialComplex229230Properties known: Dim, Facets, Name, VertexLabels, Vertices.231232Name="complex from diffcycles [ [ 1, 1, 6 ], [ 3, 3, 2 ] ]#+-complex from dif\233fcycles [ [ 1, 1, 6 ], [ 3, 3, 2 ] ]"234Dim=2235236/SimplicialComplex]237gap> SCRename(d,"T^2#T^2");238true239gap> SCLink(d,1);240[SimplicialComplex241242Properties known: Dim, Facets, Name, VertexLabels.243244Name="lk(1) in T^2#T^2"245Dim=1246247/SimplicialComplex]248gap> SCStar(d,[1,2]);249[SimplicialComplex250251Properties known: Dim, Facets, Name, VertexLabels.252253Name="star([ 1, 2 ]) in T^2#T^2"254Dim=2255256/SimplicialComplex]257gap> SCRename(c3,"T^2");258true259gap> SCConnectedProduct(c3,4);260[SimplicialComplex261262Properties known: Dim, Facets, Name, VertexLabels, Vertices.263264Name="T^2#+-T^2#+-T^2#+-T^2"265Dim=2266267/SimplicialComplex]268gap> SCCartesianProduct(c4,c4);269[SimplicialComplex270271Properties known: Dim, Facets, Name, TopologicalType, VertexLabels.272273Name="S^1_3xS^1_3"274Dim=2275TopologicalType="S^1xS^1"276277/SimplicialComplex]278gap> SCCartesianPower(c4,3);279[SimplicialComplex280281Properties known: Dim, Facets, Name, TopologicalType, VertexLabels.282283Name="(S^1_3)^3"284Dim=3285TopologicalType="(S^1)^3"286287/SimplicialComplex]288</Log>289290</Section>291292<Section Label="sec:DemoHom">293<Heading>Homology related calculations</Heading>294295<Package>simpcomp</Package> relies on the GAP package homology <Cite Key="Dumas04Homology" /> for its homology computations but provides further (co-)homology related functions, see Chapter <Ref Chap="chap:homology"/>.296297298299<Log>300gap> s2s2:=SCCartesianProduct(SCBdSimplex(3),SCBdSimplex(3));301[SimplicialComplex302303Properties known: Dim, Facets, Name, TopologicalType, VertexLabels.304305Name="S^2_4xS^2_4"306Dim=4307TopologicalType="S^2xS^2"308309/SimplicialComplex]310gap> SCHomology(s2s2);311[ [ 0, [ ] ], [ 0, [ ] ], [ 2, [ ] ], [ 0, [ ] ], [ 1, [ ] ] ]312gap> SCHomologyInternal(s2s2);313[ [ 0, [ ] ], [ 0, [ ] ], [ 2, [ ] ], [ 0, [ ] ], [ 1, [ ] ] ]314gap> SCHomologyBasis(s2s2,2);315[ [ 1, [ [ 1, 70 ], [ -1, 12 ], [ 1, 2 ], [ -1, 1 ] ] ],316[ 1, [ [ 1, 143 ], [ -1, 51 ], [ 1, 29 ], [ -1, 25 ] ] ] ]317gap> SCHomologyBasisAsSimplices(s2s2,2);318[ [ 1,319[ [ 1, [ 2, 3, 4 ] ], [ -1, [ 1, 3, 4 ] ], [ 1, [ 1, 2, 4 ] ], [ -1, [ 1320, 2, 3 ] ] ] ],321[ 1, [ [ 1, [ 5, 9, 13 ] ], [ -1, [ 1, 9, 13 ] ], [ 1, [ 1, 5, 13 ] ],322[ -1, [ 1, 5, 9 ] ] ] ] ]323gap> SCCohomologyBasis(s2s2,2);324[ [ 1,325[ [ 1, 122 ], [ 1, 115 ], [ 1, 112 ], [ 1, 111 ], [ 1, 93 ], [ 1, 90 ],326[ 1, 89 ], [ 1, 84 ], [ 1, 83 ], [ 1, 82 ], [ 1, 46 ], [ 1, 43 ],327[ 1, 42 ], [ 1, 37 ], [ 1, 36 ], [ 1, 35 ], [ 1, 28 ], [ 1, 27 ],328[ 1, 26 ], [ 1, 25 ] ] ],329[ 1, [ [ 1, 213 ], [ 1, 201 ], [ 1, 192 ], [ 1, 189 ], [ 1, 159 ],330[ 1, 150 ], [ 1, 147 ], [ 1, 131 ], [ 1, 128 ], [ 1, 125 ],331[ 1, 67 ], [ 1, 58 ], [ 1, 55 ], [ 1, 39 ], [ 1, 36 ], [ 1, 33 ],332[ 1, 10 ], [ 1, 7 ], [ 1, 4 ], [ 1, 1 ] ] ] ]333gap> SCCohomologyBasisAsSimplices(s2s2,2);334[ [ 1, [ [ 1, [ 4, 8, 12 ] ], [ 1, [ 3, 8, 12 ] ], [ 1, [ 3, 7, 12 ] ],335[ 1, [ 3, 7, 11 ] ], [ 1, [ 2, 8, 12 ] ], [ 1, [ 2, 7, 12 ] ],336[ 1, [ 2, 7, 11 ] ], [ 1, [ 2, 6, 12 ] ], [ 1, [ 2, 6, 11 ] ],337[ 1, [ 2, 6, 10 ] ], [ 1, [ 1, 8, 12 ] ], [ 1, [ 1, 7, 12 ] ],338[ 1, [ 1, 7, 11 ] ], [ 1, [ 1, 6, 12 ] ], [ 1, [ 1, 6, 11 ] ],339[ 1, [ 1, 6, 10 ] ], [ 1, [ 1, 5, 12 ] ], [ 1, [ 1, 5, 11 ] ],340[ 1, [ 1, 5, 10 ] ], [ 1, [ 1, 5, 9 ] ] ] ],341[ 1, [ [ 1, [ 13, 14, 15 ] ], [ 1, [ 9, 14, 15 ] ], [ 1, [ 9, 10, 15 ] ],342[ 1, [ 9, 10, 11 ] ], [ 1, [ 5, 14, 15 ] ], [ 1, [ 5, 10, 15 ] ],343[ 1, [ 5, 10, 11 ] ], [ 1, [ 5, 6, 15 ] ], [ 1, [ 5, 6, 11 ] ],344[ 1, [ 5, 6, 7 ] ], [ 1, [ 1, 14, 15 ] ], [ 1, [ 1, 10, 15 ] ],345[ 1, [ 1, 10, 11 ] ], [ 1, [ 1, 6, 15 ] ], [ 1, [ 1, 6, 11 ] ],346[ 1, [ 1, 6, 7 ] ], [ 1, [ 1, 2, 15 ] ], [ 1, [ 1, 2, 11 ] ],347[ 1, [ 1, 2, 7 ] ], [ 1, [ 1, 2, 3 ] ] ] ] ]348gap> PrintArray(SCIntersectionForm(s2s2));349[ [ 0, 1 ],350[ 1, 0 ] ]351gap> c:=s2s2+s2s2;352[SimplicialComplex353354Properties known: Dim, Facets, Name, VertexLabels, Vertices.355356Name="S^2_4xS^2_4#+-S^2_4xS^2_4"357Dim=4358359/SimplicialComplex]360gap> PrintArray(SCIntersectionForm(c));361[ [ 0, -1, 0, 0 ],362[ -1, 0, 0, 0 ],363[ 0, 0, 0, -1 ],364[ 0, 0, -1, 0 ] ]365</Log>366367</Section>368369<Section Label="sec:DemoBist">370<Heading>Bistellar flips</Heading>371372For a more detailed description of functions related to bistellar flips as well as a very short introduction into the topic, see Chapter <Ref Chap="chap:bistellar"/>.373<Log>374gap> beta4:=SCBdCrossPolytope(4);;375gap> s3:=SCBdSimplex(4);;376gap> SCEquivalent(beta4,s3);377#I round 0, move: [ [ 2, 6, 7 ], [ 3, 4 ] ]378[ 8, 25, 34, 17 ]379#I round 1, move: [ [ 2, 7 ], [ 3, 4, 5 ] ]380[ 8, 24, 32, 16 ]381#I round 2, move: [ [ 2, 5 ], [ 3, 4, 8 ] ]382[ 8, 23, 30, 15 ]383#I round 3, move: [ [ 2 ], [ 3, 4, 6, 8 ] ]384[ 7, 19, 24, 12 ]385#I round 4, move: [ [ 6, 8 ], [ 1, 3, 4 ] ]386[ 7, 18, 22, 11 ]387#I round 5, move: [ [ 8 ], [ 1, 3, 4, 5 ] ]388[ 6, 14, 16, 8 ]389#I round 6, move: [ [ 5 ], [ 1, 3, 4, 7 ] ]390[ 5, 10, 10, 5 ]391#I SCReduceComplexEx: complexes are bistellarly equivalent.392true393gap> SCBistellarOptions.WriteLevel;3940395gap> SCBistellarOptions.WriteLevel:=1;3961397gap> SCEquivalent(beta4,s3);398#I SCLibInit: made directory "~/PATH" for user library.399#I SCIntFunc.SCLibInit: index not found -- trying to reconstruct it.400#I SCLibUpdate: rebuilding index for ~/PATH.401#I SCLibUpdate: rebuilding index done.402403#I round 0, move: [ [ 2, 4, 6 ], [ 7, 8 ] ]404[ 8, 25, 34, 17 ]405#I round 1, move: [ [ 2, 4 ], [ 5, 7, 8 ] ]406[ 8, 24, 32, 16 ]407#I round 2, move: [ [ 4, 5 ], [ 1, 7, 8 ] ]408[ 8, 23, 30, 15 ]409#I round 3, move: [ [ 4 ], [ 1, 6, 7, 8 ] ]410[ 7, 19, 24, 12 ]411#I SCLibAdd: saving complex to file "complex_ReducedComplex_7_vertices_3_2009\412-10-27_11-40-00.sc".413#I round 4, move: [ [ 2, 6 ], [ 3, 7, 8 ] ]414[ 7, 18, 22, 11 ]415#I round 5, move: [ [ 2 ], [ 3, 5, 7, 8 ] ]416[ 6, 14, 16, 8 ]417#I SCLibAdd: saving complex to file "complex_ReducedComplex_6_vertices_5_2009\418-10-27_11-40-00.sc".419#I round 6, move: [ [ 5 ], [ 1, 3, 7, 8 ] ]420[ 5, 10, 10, 5 ]421#I SCLibAdd: saving complex to file "complex_ReducedComplex_5_vertices_6_2009\422-10-27_11-40-00.sc".423#I SCLibAdd: saving complex to file "complex_ReducedComplex_5_vertices_7_2009\424-10-27_11-40-00.sc".425#I SCReduceComplexEx: complexes are bistellarly equivalent.426true427gap> myLib:=SCLibInit("~/PATH"); # copy path from above428[Simplicial complex library. Properties:429CalculateIndexAttributes=true430Number of complexes in library=4431IndexAttributes=[ "Name", "Date", "Dim", "F", "G", "H", "Chi", "Homology" ]432Loaded=true433Path="/home/spreerjn/reducedComplexes/2009-10-27_11-40-00/"434]435gap> s3:=myLib.Load(3);436[SimplicialComplex437438Properties known: Chi, Date, Dim, F, Faces, Facets, G, H, Homology,439IsConnected, Name, VertexLabels.440441Name="ReducedComplex_5_vertices_6"442Dim=3443Chi=0444F=[ 5, 10, 10, 5 ]445G=[ 0, 0 ]446H=[ 1, 1, 1, 1 ]447Homology=[ [ 0, [ ] ], [ 0, [ ] ], [ 0, [ ] ], [ 1, [ ] ] ]448IsConnected=true449450/SimplicialComplex]451gap> s3:=myLib.Load(2);452[SimplicialComplex453454Properties known: Chi, Date, Dim, F, Faces, Facets, G, H, Homology,455IsConnected, Name, VertexLabels.456457Name="ReducedComplex_6_vertices_5"458Dim=3459Chi=0460F=[ 6, 14, 16, 8 ]461G=[ 1, 0 ]462H=[ 2, 2, 2, 1 ]463Homology=[ [ 0, [ ] ], [ 0, [ ] ], [ 0, [ ] ], [ 1, [ ] ] ]464IsConnected=true465466/SimplicialComplex]467gap> t2:=SCCartesianProduct(SCBdSimplex(2),SCBdSimplex(2));;468gap> t2.F;469[ 9, 27, 18 ]470gap> SCBistellarOptions.WriteLevel:=0;4710472gap> SCBistellarOptions.LogLevel:=0;4730474gap> mint2:=SCReduceComplex(t2);475[ true, [SimplicialComplex476477Properties known: Dim, Facets, Name, VertexLabels.478479Name="unnamed complex 85"480Dim=2481482/SimplicialComplex], 32 ]483</Log>484</Section>485486<Section Label="sec:DemoBlowups">487<Heading>Simplicial blowups</Heading>488489For a more detailed description of functions related to simplicial blowups see Chapter <Ref Chap="chap:blowups"/>.490<Log>491gap> list:=SCLib.SearchByName("Kummer");492[ [ 7493, "4-dimensional Kummer variety (VT)" ] ]493gap> c:=SCLib.Load(7493);494[SimplicialComplex495496Properties known: AltshulerSteinberg, AutomorphismGroup,497AutomorphismGroupSize, AutomorphismGroupStructure,498AutomorphismGroupTransitivity,499ConnectedComponents, Date, Dim, DualGraph,500EulerCharacteristic, FacetsEx, GVector,501GeneratorsEx, HVector, HasBoundary, HasInterior,502Homology, Interior, IsCentrallySymmetric,503IsConnected, IsEulerianManifold, IsManifold,504IsOrientable, IsPseudoManifold, IsPure,505IsStronglyConnected, MinimalNonFacesEx, Name,506Neighborliness, NumFaces[], Orientation,507SkelExs[], Vertices.508509Name="4-dimensional Kummer variety (VT)"510Dim=4511AltshulerSteinberg=45137758519296000000000000512AutomorphismGroupSize=1920513AutomorphismGroupStructure="((C2 x C2 x C2 x C2) : A5) : C2"514AutomorphismGroupTransitivity=1515EulerCharacteristic=8516GVector=[ 10, 55, 60 ]517HVector=[ 11, 66, 126, -19, 7 ]518HasBoundary=false519HasInterior=true520Homology=[ [0, [ ] ], [0, [ ] ], [6, [2,2,2,2,2] ], [0, [ ] ], [1, [ ] ] ]521IsCentrallySymmetric=false522IsConnected=true523IsEulerianManifold=true524IsOrientable=true525IsPseudoManifold=true526IsPure=true527IsStronglyConnected=true528Neighborliness=2529530/SimplicialComplex]531gap> lk:=SCLink(c,1);532[SimplicialComplex533534Properties known: Dim, FacetsEx, Name, Vertices.535536Name="lk([ 1 ]) in 4-dimensional Kummer variety (VT)"537Dim=3538539/SimplicialComplex]540gap> SCHomology(lk);541[ [ 0, [ ] ], [ 0, [ 2 ] ], [ 0, [ ] ], [ 1, [ ] ] ]542gap> SCLibDetermineTopologicalType(lk);543[ 45, 113, 2426, 2502, 7470 ]544gap> d:=SCLib.Load(45);;545gap> d.Name;546"RP^3"547gap> SCEquivalent(lk,d);548#I SCReduceComplexEx: complexes are bistellarly equivalent.549true550gap> e:=SCBlowup(c,1);551#I SCBlowup: checking if singularity is a combinatorial manifold...552#I SCBlowup: ...true553#I SCBlowup: checking type of singularity...554#I SCReduceComplexEx: complexes are bistellarly equivalent.555#I SCBlowup: ...ordinary double point (supported type).556#I SCBlowup: starting blowup...557#I SCBlowup: map boundaries...558#I SCBlowup: boundaries not isomorphic, initializing bistellar moves...559#I SCBlowup: found complex with smaller boundary: f = [ 15, 74, 118, 59 ].560#I SCBlowup: found complex with smaller boundary: f = [ 14, 70, 112, 56 ].561#I SCBlowup: found complex with smaller boundary: f = [ 14, 69, 110, 55 ].562#I SCBlowup: found complex with smaller boundary: f = [ 14, 68, 108, 54 ].563#I SCBlowup: found complex with smaller boundary: f = [ 13, 64, 102, 51 ].564#I SCBlowup: found complex with smaller boundary: f = [ 13, 63, 100, 50 ].565#I SCBlowup: found complex with smaller boundary: f = [ 13, 62, 98, 49 ].566#I SCBlowup: found complex with smaller boundary: f = [ 12, 58, 92, 46 ].567#I SCBlowup: found complex with smaller boundary: f = [ 12, 57, 90, 45 ].568#I SCBlowup: found complex with smaller boundary: f = [ 12, 56, 88, 44 ].569#I SCBlowup: found complex with smaller boundary: f = [ 11, 52, 82, 41 ].570#I SCBlowup: found complex with smaller boundary: f = [ 11, 51, 80, 40 ].571#I SCBlowup: found complex with isomorphic boundaries.572#I SCBlowup: ...boundaries mapped succesfully.573#I SCBlowup: build complex...574#I SCBlowup: ...done.575#I SCBlowup: ...blowup completed.576#I SCBlowup: You may now want to reduce the complex via 'SCReduceComplex'.577[SimplicialComplex578579Properties known: Dim, FacetsEx, Name, Vertices.580581Name="unnamed complex 6315 \ star([ 1 ]) in unnamed complex 6315 cup unnamed\582complex 6319 cup unnamed complex 6317"583Dim=4584585/SimplicialComplex]586gap> SCHomology(c);587[ [ 0, [ ] ], [ 0, [ ] ], [ 6, [ 2, 2, 2, 2, 2 ] ], [ 0, [ ] ], [ 1, [ ] ] ]588gap> SCHomology(e);589[ [ 0, [ ] ], [ 0, [ ] ], [ 7, [ 2, 2, 2, 2 ] ], [ 0, [ ] ], [ 1, [ ] ] ]590</Log>591</Section>592593594<Section Label="sec:DemoDiscreteNormalSurface">595<Heading>Discrete normal surfaces and slicings</Heading>596597For a more detailed description of functions related to discrete normal surfaces and slicings see the Sections <Ref Chap="sec:NormSurfTheory"/> and <Ref Chap="sec:MorseTheory"/>.598<Log>599600gap> # the boundary of the cyclic 4-polytope with 6 vertices601gap> c:=SCBdCyclicPolytope(4,6);602[SimplicialComplex603604Properties known: Dim, EulerCharacteristic, FacetsEx, HasBoundary, Homology,\605IsConnected, IsStronglyConnected, Name, NumFaces[], TopologicalType, Vertices.606607Name="Bd(C_4(6))"608Dim=3609EulerCharacteristic=0610HasBoundary=false611Homology=[ [ 0, [ ] ], [ 0, [ ] ], [ 0, [ ] ], [ 1, [ ] ] ]612IsConnected=true613IsStronglyConnected=true614TopologicalType="S^3"615616/SimplicialComplex]617gap> # slicing in between the odd and the even vertex labels, a polyhedral torus618gap> sl:=SCSlicing(c,[[2,4,6],[1,3,5]]);619[NormalSurface620621Properties known: ConnectedComponents, Dim, EulerCharacteristic, FVector,\622FacetsEx, Genus, IsConnected, IsOrientable, NSTriangulation, Name,\623TopologicalType, Vertices.624625Name="slicing [ [ 2, 4, 6 ], [ 1, 3, 5 ] ] of Bd(C_4(6))"626Dim=2627FVector=[ 9, 18, 0, 9 ]628EulerCharacteristic=0629IsOrientable=true630TopologicalType="T^2"631632/NormalSurface]633gap> sl.Homology;634[ [ 0, [ ] ], [ 2, [ ] ], [ 1, [ ] ] ]635gap> sl.Genus;6361637gap> sl.F; # the slicing constists of 9 quadrilaterals and 0 triangles638[ 9, 18, 0, 9 ]639gap> PrintArray(sl.Facets);640[ [ [ 2, 1 ], [ 2, 3 ], [ 4, 1 ], [ 4, 3 ] ],641[ [ 2, 1 ], [ 2, 3 ], [ 6, 1 ], [ 6, 3 ] ],642[ [ 2, 1 ], [ 2, 5 ], [ 4, 1 ], [ 4, 5 ] ],643[ [ 2, 1 ], [ 2, 5 ], [ 6, 1 ], [ 6, 5 ] ],644[ [ 2, 3 ], [ 2, 5 ], [ 4, 3 ], [ 4, 5 ] ],645[ [ 2, 3 ], [ 2, 5 ], [ 6, 3 ], [ 6, 5 ] ],646[ [ 4, 1 ], [ 4, 3 ], [ 6, 1 ], [ 6, 3 ] ],647[ [ 4, 1 ], [ 4, 5 ], [ 6, 1 ], [ 6, 5 ] ],648[ [ 4, 3 ], [ 4, 5 ], [ 6, 3 ], [ 6, 5 ] ] ]649</Log></Section>650651Further example computations can be found in the slides of various talks about <Package>simpcomp</Package>, available from the <Package>simpcomp</Package> homepage (<C>https://github.com/simpcomp-team/simpcomp</C>), and in Appendix A of <Cite Key="Spreer10Diss"/>.652</Chapter>653654655656