politopix  5.0.0
Neighbours_Rn Class Reference

Class dedicated to degeneration processing when looking for neighbours.
Let A be a polytope of \( \mathbb{R}^n, A = H_1^+ \cap H_2^+ \cap ... H_{n-1}^+ \cap ... H_k^+ \) where k>n.
Let [vi, vj] be a segment of two vertices of A such as: More...

#include <Neighbours_Rn.h>

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Public Member Functions

 Neighbours_Rn ()
 
void addGenerator (const std::vector< unsigned int > &commonFacets, unsigned int numbergenIN, unsigned int numbergenOUT, HalfSpace_Rn::State state)
 Tell whether a pseudo neighbor is a genuine one comparing set of half-spaces. More...
 
void addGeneratorWithoutCheck (const std::vector< unsigned int > &commonFacets, unsigned int numbergenIN, unsigned int numbergenOUT, HalfSpace_Rn::State state)
 
void begin ()
 Iterator function. More...
 
void next ()
 Iterator function. More...
 
void checkIterator ()
 Make sure we don't point on a generator with state ON. More...
 
bool end () const
 Iterator function. More...
 
unsigned int currentGenInNumber () const
 Iterator function. More...
 
unsigned int currentGenOutNumber () const
 Iterator function. More...
 
const std::vector< unsigned int > & commonHalfSpaces () const
 Iterator function. More...
 
void dump (std::ostream &ofs) const
 Display the content on the stream passed as an argument. More...
 

Protected Attributes

unsigned int _iterator
 A runner to iterate through the list of genuine neighbors. More...
 
std::vector< HalfSpace_Rn::State_GeneratorsState
 The pair of generators state. More...
 
std::vector< unsigned int > _GeneratorsInNumber
 The generator numbers IN in a global list. More...
 
std::vector< unsigned int > _GeneratorsOutNumber
 The generator numbers OUT in a global list. More...
 
std::vector< std::vector< unsigned int > > _HSPerNewGenerators
 For each generator, store all raw pointers on their corresponding half-spaces. More...
 

Detailed Description

Class dedicated to degeneration processing when looking for neighbours.
Let A be a polytope of \( \mathbb{R}^n, A = H_1^+ \cap H_2^+ \cap ... H_{n-1}^+ \cap ... H_k^+ \) where k>n.
Let [vi, vj] be a segment of two vertices of A such as:

  • they share (n-1) hyperplanes in common: \( H_{ij} = \{ H_1, H_2, ... H_{n-1} \} \)
  • there exists an hyperplane \( \mathcal{H} \) separating [vj, vk]

We call [vi, vj] a pseudo-edge if it respects the first assumption. The question is: to which condition [vi, vj] is a genuine edge? Can we answer the question only by processing the pseudo-edges separated by the hyperplane \( \mathcal{H} \)? The straight line \( (v_i, v_j) \subset H_1 \cap H_2 \cap ... H_{n-1} \text{~with~} \mathcal{H} \neq H_u \), \( u \in \{ 1, ..., n-1 \} \). So \( H_1 \cap H_2 \cap ... H_{n-1} \cap H_n^+ \cap ... H_k^+ = F_A \) is a face of A of dimension at least 1. Let's assume [vi, vj] is not an edge of A, then it is not an edge of FA and we cannot have FA included neither in \( \mathcal{H}^+ \) nor in \( \mathcal{H}^- \) as \( \mathcal{H} \) separates [vi, vj] . So \( \mathcal{H} \) separates FA and we can find an edge [va, vb] of FA such as:

  • \( \mathcal{H} \) separates [va, vb] or
  • \( \mathcal{H} \) passes through va or
  • \( \mathcal{H} \) passes through vb

As [va, vb] is an edge of FA, va and vb share in common the list of hyperplanes Hab . Hab contains the (n-1) half-spaces \( H_1, H_2, ... H_{n-1} \) and others because the intersection \( H_1 \cap H_2 \cap ... H_{n-1} \) does not define a straight line. So if [vi, vj] is not an edge of A, we can find a genuine edge [va, vb] , intersecting with \( \mathcal{H} \), such as \( H_{ij} \subset H_{ab} \)

Definition at line 59 of file Neighbours_Rn.h.

Constructor & Destructor Documentation

◆ Neighbours_Rn()

Neighbours_Rn::Neighbours_Rn ( )
inline

Definition at line 62 of file Neighbours_Rn.h.

Member Function Documentation

◆ addGenerator()

void Neighbours_Rn::addGenerator ( const std::vector< unsigned int > &  commonFacets,
unsigned int  numbergenIN,
unsigned int  numbergenOUT,
HalfSpace_Rn::State  state 
)
inline

Tell whether a pseudo neighbor is a genuine one comparing set of half-spaces.

Parameters
commonFacetsthe set of common half-spaces pointers between this and gen
numbergenINthe generator number candidate to be a genuine end of edge
numbergenOUTthe generator number candidate to be the other genuine end of edge
stateequal to HalfSpace_Rn::hs_IN_OR_OUT or HalfSpace_Rn::hs_ON according to the edge property

Definition at line 69 of file Neighbours_Rn.h.

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◆ addGeneratorWithoutCheck()

void Neighbours_Rn::addGeneratorWithoutCheck ( const std::vector< unsigned int > &  commonFacets,
unsigned int  numbergenIN,
unsigned int  numbergenOUT,
HalfSpace_Rn::State  state 
)
inline

Definition at line 127 of file Neighbours_Rn.h.

◆ begin()

void Neighbours_Rn::begin ( )
inline

Iterator function.

Definition at line 139 of file Neighbours_Rn.h.

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◆ checkIterator()

void Neighbours_Rn::checkIterator ( )
inline

Make sure we don't point on a generator with state ON.

Definition at line 145 of file Neighbours_Rn.h.

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◆ commonHalfSpaces()

const std::vector< unsigned int >& Neighbours_Rn::commonHalfSpaces ( ) const
inline

Iterator function.

Definition at line 160 of file Neighbours_Rn.h.

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◆ currentGenInNumber()

unsigned int Neighbours_Rn::currentGenInNumber ( ) const
inline

Iterator function.

Definition at line 154 of file Neighbours_Rn.h.

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◆ currentGenOutNumber()

unsigned int Neighbours_Rn::currentGenOutNumber ( ) const
inline

Iterator function.

Definition at line 157 of file Neighbours_Rn.h.

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◆ dump()

void Neighbours_Rn::dump ( std::ostream &  ofs) const
inline

Display the content on the stream passed as an argument.

Definition at line 163 of file Neighbours_Rn.h.

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◆ end()

bool Neighbours_Rn::end ( ) const
inline

Iterator function.

Definition at line 151 of file Neighbours_Rn.h.

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◆ next()

void Neighbours_Rn::next ( )
inline

Iterator function.

Definition at line 142 of file Neighbours_Rn.h.

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Member Data Documentation

◆ _GeneratorsInNumber

std::vector< unsigned int > Neighbours_Rn::_GeneratorsInNumber
protected

The generator numbers IN in a global list.

Definition at line 183 of file Neighbours_Rn.h.

◆ _GeneratorsOutNumber

std::vector< unsigned int > Neighbours_Rn::_GeneratorsOutNumber
protected

The generator numbers OUT in a global list.

Definition at line 185 of file Neighbours_Rn.h.

◆ _GeneratorsState

std::vector< HalfSpace_Rn::State > Neighbours_Rn::_GeneratorsState
protected

The pair of generators state.

Definition at line 181 of file Neighbours_Rn.h.

◆ _HSPerNewGenerators

std::vector< std::vector< unsigned int > > Neighbours_Rn::_HSPerNewGenerators
protected

For each generator, store all raw pointers on their corresponding half-spaces.

Definition at line 187 of file Neighbours_Rn.h.

◆ _iterator

unsigned int Neighbours_Rn::_iterator
protected

A runner to iterate through the list of genuine neighbors.

Definition at line 179 of file Neighbours_Rn.h.


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