tropicalTraversal.cc File Reference

#include <bbcone.h>
#include <groebnerCone.h>
#include <tropicalCurves.h>

Go to the source code of this file.

Functions
std::vector< bool >	checkNecessaryTropicalFlips (const groebnerCones &tropicalVariety, const groebnerCones &workingList, const gfan::ZVector &interiorPoint, const gfan::ZMatrix &normalVectors)
groebnerCones	tropicalTraversalMinimizingFlips (const groebnerCone startingCone)
std::vector< bool >	checkNecessaryGroebnerFlips (const groebnerCones &groebnerFan, const groebnerCones &workingList, const gfan::ZMatrix &interiorPoints)
groebnerCones	groebnerTraversal (const groebnerCone startingCone)

Function Documentation

std::vector<bool> checkNecessaryGroebnerFlips	(	const groebnerCones &	groebnerFan,
		const groebnerCones &	workingList,
		const gfan::ZMatrix &	interiorPoints
	)

Definition at line 98 of file tropicalTraversal.cc.

{
  int k = interiorPoints.getHeight();
  std::vector<bool> needToFlip(k,true);

  for (groebnerCones::iterator sigma = groebnerFan.begin(); sigma!=groebnerFan.end(); sigma++)
  {
    for (int i=0; i<k; i++)
    {
      if (needToFlip[i] && sigma->contains(interiorPoints[i]))
        needToFlip[i] = false;
    }
  }

  for (groebnerCones::iterator sigma = workingList.begin(); sigma!=workingList.end(); sigma++)
  {
    for (int i=0; i<k; i++)
    {
      if (needToFlip[i] && sigma->contains(interiorPoints[i]))
        needToFlip[i] = false;
    }
  }

  return needToFlip;
}

std::vector<bool> checkNecessaryTropicalFlips	(	const groebnerCones &	tropicalVariety,
		const groebnerCones &	workingList,
		const gfan::ZVector &	interiorPoint,
		const gfan::ZMatrix &	normalVectors
	)

Definition at line 5 of file tropicalTraversal.cc.

{
  int k = normalVectors.getHeight();
  std::vector<bool> needToFlip(k,true);

  int n = normalVectors.getWidth();
  gfan::ZMatrix testVectors(k,n);
  gfan::ZVector bigInteriorPoint = 1000*interiorPoint;
  for (int i=0; i<k; i++)
    testVectors[i] = bigInteriorPoint+normalVectors[i];

  for (groebnerCones::iterator sigma = tropicalVariety.begin(); sigma!=tropicalVariety.end(); sigma++)
  {
    if (sigma->contains(interiorPoint))
    {
      for (int i=0; i<k; i++)
      {
        if (needToFlip[i] && sigma->contains(testVectors[i]))
          needToFlip[i] = false;
      }
    }
  }

  for (groebnerCones::iterator sigma = workingList.begin(); sigma!=workingList.end(); sigma++)
  {
    if (sigma->contains(interiorPoint))
    {
      for (int i=0; i<k; i++)
      {
        if (needToFlip[i] && sigma->contains(testVectors[i]))
          needToFlip[i] = false;
      }
    }
  }

  return needToFlip;
}

groebnerCones groebnerTraversal

(

const groebnerCone

startingCone

)

Pick a maximal Groebner cone from the working list and compute interior points on its facets as well as outer facet normals

Definition at line 126 of file tropicalTraversal.cc.

{
  const tropicalStrategy* currentStrategy = startingCone.getTropicalStrategy();

  groebnerCones groebnerFan;
  groebnerCones workingList;
  workingList.insert(startingCone);
  std::set<gfan::ZVector> finishedInteriorPoints;
  bool onlyLowerHalfSpace = !currentStrategy->isValuationTrivial();

  while(!workingList.empty())
  {
    /**
     * Pick a maximal Groebner cone from the working list
     * and compute interior points on its facets as well as outer facet normals
     */
    groebnerCone sigma=*(workingList.begin());
    workingList.erase(workingList.begin());

    std::pair<gfan::ZMatrix,gfan::ZMatrix> interiorPointsAndOuterFacetNormals = interiorPointsAndNormalsOfFacets(sigma.getPolyhedralCone(), finishedInteriorPoints, onlyLowerHalfSpace);
    gfan::ZMatrix interiorPoints = interiorPointsAndOuterFacetNormals.first;
    gfan::ZMatrix outerFacetNormals = interiorPointsAndOuterFacetNormals.second;
    std::vector<bool> needToFlip = checkNecessaryGroebnerFlips(groebnerFan,workingList, interiorPoints);

    for (int i=0; i<interiorPoints.getHeight(); i++)
    {
      gfan::ZVector interiorPoint = interiorPoints[i];

      if (needToFlip[i]==true)
      {
        groebnerCone neighbour = sigma.flipCone(interiorPoint,outerFacetNormals[i]);
        workingList.insert(neighbour);
      }
      finishedInteriorPoints.insert(interiorPoints[i]);
    }

    sigma.deletePolynomialData();
    groebnerFan.insert(sigma);
    if (printlevel > 0)
      Print("cones finished: %lu   cones in working list: %lu\n",
      (unsigned long)groebnerFan.size(), (unsigned long)workingList.size());
  }
  return groebnerFan;
}

groebnerCones tropicalTraversalMinimizingFlips

(

const groebnerCone

startingCone

)

Pick an element the working list and compute interior points on its facets

For each interior point, compute the rays of the tropical star in that point

Definition at line 44 of file tropicalTraversal.cc.

{
  groebnerCones tropicalVariety;
  groebnerCones workingList;
  workingList.insert(startingCone);
  const tropicalStrategy* currentStrategy=startingCone.getTropicalStrategy();
  std::set<gfan::ZVector> finishedInteriorPoints;
  while(!workingList.empty())
  {
    /**
     * Pick an element the working list and compute interior points on its facets
     */
    groebnerCone sigma=*(workingList.begin());
    gfan::ZMatrix interiorPoints = interiorPointsOfFacets(sigma.getPolyhedralCone(),finishedInteriorPoints);

    for (int i=0; i<interiorPoints.getHeight(); i++)
    {
      /**
       * For each interior point, compute the rays of the tropical star in that point
       */
      gfan::ZVector interiorPoint = interiorPoints[i];
      if (!(currentStrategy->restrictToLowerHalfSpace() && interiorPoint[0].sign()==0))
      {
        ideal inI = initial(sigma.getPolynomialIdeal(),sigma.getPolynomialRing(),interiorPoint);
        gfan::ZMatrix normalVectors = raysOfTropicalStar(inI,
                                                         sigma.getPolynomialRing(),
                                                         interiorPoint,
                                                         sigma.getTropicalStrategy());
        id_Delete(&inI,sigma.getPolynomialRing());

        std::vector<bool> needToFlip = checkNecessaryTropicalFlips(tropicalVariety,workingList,interiorPoint,normalVectors);
        for (int j=0; j<normalVectors.getHeight(); j++)
        {
          if (needToFlip[j])
          {
            groebnerCone neighbour = sigma.flipCone(interiorPoint,normalVectors[j]);
            workingList.insert(neighbour);
          }
        }
      }
      finishedInteriorPoints.insert(interiorPoint);
    }

    sigma.deletePolynomialData();
    workingList.erase(sigma);
    tropicalVariety.insert(sigma);
    if (printlevel > 0)
      Print("cones finished: %lu   cones in working list: %lu\n",
      (unsigned long)tropicalVariety.size(), (unsigned long)workingList.size());
  }
  return tropicalVariety;
}