Regina Calculation Engine
Public Member Functions | Static Public Member Functions | List of all members
regina::NLayeredChain Class Reference

Represents a layered chain in a triangulation. More...

#include <subcomplex/nlayeredchain.h>

Inheritance diagram for regina::NLayeredChain:
regina::NStandardTriangulation regina::ShareableObject regina::boost::noncopyable

Public Member Functions

 NLayeredChain (NTetrahedron *tet, NPerm4 vertexRoles)
 Creates a new layered chain containing only the given tetrahedron. More...
 
 NLayeredChain (const NLayeredChain &cloneMe)
 Creates a new layered chain that is a clone of the given structure. More...
 
virtual ~NLayeredChain ()
 Destroys this layered chain. More...
 
NTetrahedrongetBottom () const
 Returns the bottom tetrahedron of this layered chain. More...
 
NTetrahedrongetTop () const
 Returns the top tetrahedron of this layered chain. More...
 
unsigned long getIndex () const
 Returns the number of tetrahedra in this layered chain. More...
 
NPerm4 getBottomVertexRoles () const
 Returns a permutation represeting the role that each vertex of the bottom tetrahedron plays in the layered chain. More...
 
NPerm4 getTopVertexRoles () const
 Returns a permutation represeting the role that each vertex of the top tetrahedron plays in the layered chain. More...
 
bool extendAbove ()
 Checks to see whether this layered chain can be extended to include the tetrahedron above the top tetrahedron (and still remain a layered chain). More...
 
bool extendBelow ()
 Checks to see whether this layered chain can be extended to include the tetrahedron below the bottom tetrahedron (and still remain a layered chain). More...
 
bool extendMaximal ()
 Extends this layered chain to a maximal length layered chain. More...
 
void reverse ()
 Reverses this layered chain so the top tetrahedron becomes the bottom and vice versa. More...
 
void invert ()
 Inverts this layered chain so the upper hinge becomes the lower and vice versa. More...
 
NManifoldgetManifold () const
 Returns the 3-manifold represented by this triangulation, if such a recognition routine has been implemented. More...
 
NAbelianGroupgetHomologyH1 () const
 Returns the expected first homology group of this triangulation, if such a routine has been implemented. More...
 
std::ostream & writeName (std::ostream &out) const
 Writes the name of this triangulation as a human-readable string to the given output stream. More...
 
std::ostream & writeTeXName (std::ostream &out) const
 Writes the name of this triangulation in TeX format to the given output stream. More...
 
void writeTextLong (std::ostream &out) const
 Writes this object in long text format to the given output stream. More...
 
std::string getName () const
 Returns the name of this specific triangulation as a human-readable string. More...
 
std::string getTeXName () const
 Returns the name of this specific triangulation in TeX format. More...
 
virtual void writeTextShort (std::ostream &out) const
 Writes this object in short text format to the given output stream. More...
 
Input and Output
std::string str () const
 Returns the output from writeTextShort() as a string. More...
 
std::string toString () const
 A deprecated alias for str(), which returns the output from writeTextShort() as a string. More...
 
std::string detail () const
 Returns the output from writeTextLong() as a string. More...
 
std::string toStringLong () const
 A deprecated alias for detail(), which returns the output from writeTextLong() as a string. More...
 

Static Public Member Functions

static NStandardTriangulationisStandardTriangulation (NComponent *component)
 Determines whether the given component represents one of the standard triangulations understood by Regina. More...
 
static NStandardTriangulationisStandardTriangulation (NTriangulation *tri)
 Determines whether the given triangulation represents one of the standard triangulations understood by Regina. More...
 

Detailed Description

Represents a layered chain in a triangulation.

A layered chain is a set of n tetrahedra glued to each other by layerings. For each tetrahedron, select two top faces, two bottom faces and two hinge edges, so that the top faces are adjacent, the bottom faces are adjacent, the hinge edges are opposite and each hinge meets both a top and a bottom face. The tetrahedron can thus be thought of as a fattened square with the top and bottom faces above and below the square respectively, and the hinges as the top and bottom edges of the square. The left and right edges of the square are identified to form an annulus.

For each i, the top faces of tetrahedron i are glued to the bottom faces of tetrahedron i+1. This is done by layering the upper tetrahedron upon the annulus formed by the top faces of the lower tetrahedron. The layering should be done over the left or right edge of the lower square (note that these two edges are actually identified). The top hinges of each tetrahedron should be identified, as should the bottom hinges.

The bottom faces of the first tetrahedron and the top faces of the last tetrahedron form the boundary of the layered chain. If there is more than one tetrahedron, the layered chain forms a solid torus with two vertices whose axis is parallel to each hinge edge.

The index of the layered chain is the number of tetrahedra it contains. A layered chain must contain at least one tetrahedron.

Note that for the purposes of getManifold() and getHomologyH1(), a layered chain containing only one tetrahedron will be considered as a standalone tetrahedron that forms a 3-ball (and not a solid torus).

All optional NStandardTriangulation routines are implemented for this class.

Constructor & Destructor Documentation

regina::NLayeredChain::NLayeredChain ( NTetrahedron tet,
NPerm4  vertexRoles 
)
inline

Creates a new layered chain containing only the given tetrahedron.

This new layered chain will have index 1, but may be extended using extendAbove(), extendBelow() or extendMaximal().

Parameters
tetthe tetrahedron that will make up this layered chain.
vertexRolesa permutation describing the role each tetrahedron vertex must play in the layered chain; this must be in the same format as the permutation returned by getBottomVertexRoles() and getTopVertexRoles().
regina::NLayeredChain::NLayeredChain ( const NLayeredChain cloneMe)
inline

Creates a new layered chain that is a clone of the given structure.

Parameters
cloneMethe layered chain to clone.
regina::NLayeredChain::~NLayeredChain ( )
inlinevirtual

Destroys this layered chain.

Member Function Documentation

std::string regina::ShareableObject::detail ( ) const
inherited

Returns the output from writeTextLong() as a string.

Returns
a long text representation of this object.
bool regina::NLayeredChain::extendAbove ( )

Checks to see whether this layered chain can be extended to include the tetrahedron above the top tetrahedron (and still remain a layered chain).

If so, this layered chain will be modified accordingly (note that its index will be increased by one and its top tetrahedron will change).

Returns
true if and only if this layered chain was extended.
bool regina::NLayeredChain::extendBelow ( )

Checks to see whether this layered chain can be extended to include the tetrahedron below the bottom tetrahedron (and still remain a layered chain).

If so, this layered chain will be modified accordingly (note that its index will be increased by one and its bottom tetrahedron will change).

Returns
true if and only if this layered chain was extended.
bool regina::NLayeredChain::extendMaximal ( )

Extends this layered chain to a maximal length layered chain.

Both extendAbove() and extendBelow() will be used until this layered chain can be extended no further.

Returns
true if and only if this layered chain was extended.
NTetrahedron * regina::NLayeredChain::getBottom ( ) const
inline

Returns the bottom tetrahedron of this layered chain.

Returns
the bottom tetrahedron.
NPerm4 regina::NLayeredChain::getBottomVertexRoles ( ) const
inline

Returns a permutation represeting the role that each vertex of the bottom tetrahedron plays in the layered chain.

The permutation returned (call this p) maps 0, 1, 2 and 3 to the four vertices of the bottom tetrahedron so that the edge from p[0] to p[1] is the top hinge, the edge from p[2] to p[3] is the bottom hinge, faces p[1] and p[2] are the (boundary) bottom faces and faces p[0] and p[3] are the top faces.

See the general class notes for further details.

Returns
a permutation representing the roles of the vertices of the bottom tetrahedron.
NAbelianGroup* regina::NLayeredChain::getHomologyH1 ( ) const
virtual

Returns the expected first homology group of this triangulation, if such a routine has been implemented.

If the calculation of homology has not yet been implemented for this triangulation then this routine will return 0.

This routine does not work by calling NTriangulation::getHomologyH1() on the associated real triangulation. Instead the homology is calculated directly from the known properties of this standard triangulation.

The details of which standard triangulations have homology calculation routines can be found in the notes for the corresponding subclasses of NStandardTriangulation. The default implementation of this routine returns 0.

The homology group will be newly allocated and must be destroyed by the caller of this routine.

If this NStandardTriangulation describes an entire NTriangulation (and not just a part thereof) then the results of this routine should be identical to the homology group obtained by calling NTriangulation::getHomologyH1() upon the associated real triangulation.

Returns
the first homology group of this triangulation, or 0 if the appropriate calculation routine has not yet been implemented.

Reimplemented from regina::NStandardTriangulation.

unsigned long regina::NLayeredChain::getIndex ( ) const
inline

Returns the number of tetrahedra in this layered chain.

Returns
the number of tetrahedra.
NManifold* regina::NLayeredChain::getManifold ( ) const
virtual

Returns the 3-manifold represented by this triangulation, if such a recognition routine has been implemented.

If the 3-manifold cannot be recognised then this routine will return 0.

The details of which standard triangulations have 3-manifold recognition routines can be found in the notes for the corresponding subclasses of NStandardTriangulation. The default implementation of this routine returns 0.

It is expected that the number of triangulations whose underlying 3-manifolds can be recognised will grow between releases.

The 3-manifold will be newly allocated and must be destroyed by the caller of this routine.

Returns
the underlying 3-manifold.

Reimplemented from regina::NStandardTriangulation.

std::string regina::NStandardTriangulation::getName ( ) const
inherited

Returns the name of this specific triangulation as a human-readable string.

Returns
the name of this triangulation.
std::string regina::NStandardTriangulation::getTeXName ( ) const
inherited

Returns the name of this specific triangulation in TeX format.

No leading or trailing dollar signs will be included.

Warning
The behaviour of this routine has changed as of Regina 4.3; in earlier versions, leading and trailing dollar signs were provided.
Returns
the name of this triangulation in TeX format.
NTetrahedron * regina::NLayeredChain::getTop ( ) const
inline

Returns the top tetrahedron of this layered chain.

Returns
the top tetrahedron.
NPerm4 regina::NLayeredChain::getTopVertexRoles ( ) const
inline

Returns a permutation represeting the role that each vertex of the top tetrahedron plays in the layered chain.

The permutation returned (call this p) maps 0, 1, 2 and 3 to the four vertices of the top tetrahedron so that the edge from p[0] to p[1] is the top hinge, the edge from p[2] to p[3] is the bottom hinge, faces p[1] and p[2] are the bottom faces and faces p[0] and p[3] are the (boundary) top faces.

See the general class notes for further details.

Returns
a permutation representing the roles of the vertices of the top tetrahedron.
void regina::NLayeredChain::invert ( )

Inverts this layered chain so the upper hinge becomes the lower and vice versa.

The top and bottom tetrahedra will remain the top and bottom tetrahedra respectively.

Note that this operation will cause the hinge edges to point in the opposite direction around the solid torus formed by this layered chain.

Note that only the representation of the chain is altered; the underlying triangulation is not changed.

static NStandardTriangulation* regina::NStandardTriangulation::isStandardTriangulation ( NComponent component)
staticinherited

Determines whether the given component represents one of the standard triangulations understood by Regina.

The list of recognised triangulations is expected to grow between releases.

If the standard triangulation returned has boundary triangles then the given component must have the same corresponding boundary triangles, i.e., the component cannot have any further identifications of these boundary triangles with each other.

Note that the triangulation-based routine isStandardTriangulation(NTriangulation*) may recognise more triangulations than this routine, since passing an entire triangulation allows access to more information.

Parameters
componentthe triangulation component under examination.
Returns
the details of the standard triangulation if the given component is recognised, or 0 otherwise.
static NStandardTriangulation* regina::NStandardTriangulation::isStandardTriangulation ( NTriangulation tri)
staticinherited

Determines whether the given triangulation represents one of the standard triangulations understood by Regina.

The list of recognised triangulations is expected to grow between releases.

If the standard triangulation returned has boundary triangles then the given triangulation must have the same corresponding boundary triangles, i.e., the triangulation cannot have any further identifications of these boundary triangles with each other.

This routine may recognise more triangulations than the component-based isStandardTriangulation(NComponent*), since passing an entire triangulation allows access to more information.

Parameters
trithe triangulation under examination.
Returns
the details of the standard triangualation if the given triangulation is recognised, or 0 otherwise.
void regina::NLayeredChain::reverse ( )

Reverses this layered chain so the top tetrahedron becomes the bottom and vice versa.

The upper and lower hinges will remain the upper and lower hinges respectively.

Note that this operation will cause the hinge edges to point in the opposite direction around the solid torus formed by this layered chain.

Note that only the representation of the chain is altered; the underlying triangulation is not changed.

std::string regina::ShareableObject::str ( ) const
inherited

Returns the output from writeTextShort() as a string.

Python:
This implements the __str__() function.
Returns
a short text representation of this object.
std::string regina::ShareableObject::toString ( ) const
inlineinherited

A deprecated alias for str(), which returns the output from writeTextShort() as a string.

Deprecated:
This routine has (at long last) been deprecated; use the simpler-to-type str() instead.
Returns
a short text representation of this object.
std::string regina::ShareableObject::toStringLong ( ) const
inlineinherited

A deprecated alias for detail(), which returns the output from writeTextLong() as a string.

Deprecated:
This routine has (at long last) been deprecated; use the simpler-to-type detail() instead.
Returns
a long text representation of this object.
std::ostream & regina::NLayeredChain::writeName ( std::ostream &  out) const
inlinevirtual

Writes the name of this triangulation as a human-readable string to the given output stream.

Python:
The parameter out does not exist; standard output will be used.
Parameters
outthe output stream to which to write.
Returns
a reference to the given output stream.

Implements regina::NStandardTriangulation.

std::ostream & regina::NLayeredChain::writeTeXName ( std::ostream &  out) const
inlinevirtual

Writes the name of this triangulation in TeX format to the given output stream.

No leading or trailing dollar signs will be included.

Warning
The behaviour of this routine has changed as of Regina 4.3; in earlier versions, leading and trailing dollar signs were provided.
Python:
The parameter out does not exist; standard output will be used.
Parameters
outthe output stream to which to write.
Returns
a reference to the given output stream.

Implements regina::NStandardTriangulation.

void regina::NLayeredChain::writeTextLong ( std::ostream &  out) const
inlinevirtual

Writes this object in long text format to the given output stream.

The output should provide the user with all the information they could want. The output should be human-readable, should not contain extremely long lines (so users can read the output in a terminal), and should end with a final newline.

The default implementation of this routine merely calls writeTextShort() and adds a newline.

Python:
The parameter out does not exist; standard output will be used.
Parameters
outthe output stream to which to write.

Reimplemented from regina::ShareableObject.

void regina::NStandardTriangulation::writeTextShort ( std::ostream &  out) const
inlinevirtualinherited

Writes this object in short text format to the given output stream.

The output should be human-readable, should fit on a single line, and should not end with a newline.

Python:
The parameter out does not exist; standard output will be used.
Parameters
outthe output stream to which to write.

Implements regina::ShareableObject.


The documentation for this class was generated from the following file:

Copyright © 1999-2014, The Regina development team
This software is released under the GNU General Public License, with some additional permissions; see the source code for details.
For further information, or to submit a bug or other problem, please contact Ben Burton (bab@debian.org).