message: Move Edge collapse section
diff: </tr>
  </table>
  -### Witness complex
  +### Edge collapse
  <table>
  <tr>
  <td width="35%" rowspan=2>
  - \image html "Witness_complex_representation.png"
  + \image html "edge_collapse_representation.png"
  </td>
  <td width="50%">
  - Witness complex \f$ Wit(W,L) \f$ is a simplicial complex defined on two sets of points in \f$\mathbb{R}^D\f$.
  - The data structure is described in \cite boissonnatmariasimplextreealgorithmica .
  + Edge collapse is able to reduce any flag filtration to a smaller flag filtration with the same persistence, using
  + only the 1-skeletons of a simplicial complex.
  + The reduction is exact and the persistence homology of the reduced sequence is identical to the persistence
  + homology of the input sequence. The resulting method is simple and extremely efficient.
  +
  + Computation of edge collapse and persistent homology of a filtered flag complex via edge collapse as described in
  + \cite edgecollapsesocg2020.
  </td>
  <td width="15%">
  - <b>Author:</b> Siargey Kachanovich<br>
  - <b>Introduced in:</b> GUDHI 1.3.0<br>
  - <b>Copyright:</b> MIT ([GPL v3](../../licensing/) for Euclidean version)<br>
  - <b>Euclidean version requires:</b> \ref eigen &ge; 3.1.0 and \ref cgal &ge; 4.11.0
  + <b>Author:</b> Siddharth Pritam<br>
  + <b>Introduced in:</b> GUDHI 2.4.0<br>
  + <b>Copyright:</b> MIT<br>
  + <b>Requires:</b> \ref eigen
  </td>
  </tr>
  <tr>
  <td colspan=2 height="25">
  - <b>User manual:</b> \ref witness_complex
  + <b>User manual:</b> \ref edge_collapse
  </td>
  </tr>
  </table>
  -#### Edge collapse
  +### Witness complex
  <table>
  <tr>
  <td width="35%" rowspan=2>
  - \image html "edge_collapse_representation.png"
  + \image html "Witness_complex_representation.png"
  </td>
  <td width="50%">
  - Edge collapse is able to reduce any flag filtration to a smaller flag filtration with the same persistence, using
  - only the 1-skeletons of a simplicial complex.
  - The reduction is exact and the persistence homology of the reduced sequence is identical to the persistence
  - homology of the input sequence. The resulting method is simple and extremely efficient.
  -
  - Computation of edge collapse and persistent homology of a filtered flag complex via edge collapse as described in
  - \cite edgecollapsesocg2020.
  + Witness complex \f$ Wit(W,L) \f$ is a simplicial complex defined on two sets of points in \f$\mathbb{R}^D\f$.
  + The data structure is described in \cite boissonnatmariasimplextreealgorithmica .
  </td>
  <td width="15%">
  - <b>Author:</b> Siddharth Pritam<br>
  - <b>Introduced in:</b> GUDHI 2.4.0<br>
  - <b>Copyright:</b> MIT<br>
  - <b>Requires:</b> \ref eigen
  + <b>Author:</b> Siargey Kachanovich<br>
  + <b>Introduced in:</b> GUDHI 1.3.0<br>
  + <b>Copyright:</b> MIT ([GPL v3](../../licensing/) for Euclidean version)<br>
  + <b>Euclidean version requires:</b> \ref eigen &ge; 3.1.0 and \ref cgal &ge; 4.11.0
  </td>
  </tr>
  <tr>
  <td colspan=2 height="25">
  - <b>User manual:</b> \ref edge_collapse
  + <b>User manual:</b> \ref witness_complex
  </td>
  </tr>
  </table>
  