<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=ISO-8859-1">
</head>
<body text="#000000" bgcolor="#FFFFFF">
Dear Peter, <br>
<br>
I have a question on the PrepareContractionHierarchies algo. <br>
<br>
There is a class LevelEdgeFilterCH, which is used in the Dijkstra to
check if the shortest path between two non-contracted nodes pass
through a node that we want to contract. <br>
<br>
My point is that this class inherits from LevelEdgeFilter, and uses
its check, <br>
and I do not understand why; I fear that there is something I do not
understand. <br>
<br>
LevelEdgeFilter prevents us from strictly going down in the
hierarchy. <br>
and LevelEdgeFilterCH check this condition first. <br>
If it is OK, it further check that the neighbour node is not
contracted, that is: of level zero. <br>
Knowing that the source node is also non-contracted, this second
check seems stronger than the first check inherited from the
LevelEdgeFilter class. <br>
<br>
Thank you for your help. <br>
<br>
<div class="moz-signature">-- <br>
<table width="400" cellspacing="0">
<tbody>
<tr>
<td colspan="2" style="border-left: 1px solid rgb(0, 102,
0); background-color: rgb(255, 255, 255); font-family:
arial; font-style: normal; font-variant: normal;
font-weight: normal; font-size: 14px; line-height: normal;
font-size-adjust: none; font-stretch: normal;
vertical-align: top;"> <b>Renaud De Landtsheer, Ir, Phd</b>
</td>
</tr>
<tr>
<td colspan="2" style="border-left: 1px solid rgb(0, 102,
0); background-color: rgb(255, 255, 255); font-family:
arial; font-style: italic; font-variant: normal;
font-weight: normal; font-size: 14px; line-height: normal;
font-size-adjust: none; font-stretch: normal;
vertical-align: top;">Sr R&D Engineer</td>
</tr>
<tr>
<td colspan="2" style="border-left: 1px solid rgb(0, 102,
0); background-color: rgb(255, 255, 255); font-family:
arial; font-style: normal; font-variant: small-caps;
font-weight: normal; font-size: 14px; line-height: normal;
font-size-adjust: none; font-stretch: normal;
vertical-align: top;">
CETIC <br>
Rue des Frères Wright, 29/3 <br>
B-6041 Charleroi <br>
Phone: +32 71 490 754 </td>
</tr>
<tr>
<td colspan="2" style="border-top: 1px solid rgb(0, 102, 0);
background-color: rgb(255, 255, 255); font-family: arial;
font-style: italic; font-variant: normal; font-weight:
normal; font-size: 12px; line-height: normal;
font-size-adjust: none; font-stretch: normal;
vertical-align: top;" align="top">
<p><br>
</p>
</td>
</tr>
</tbody>
</table>
</div>
</body>
</html>