simplifying the XSL for an intersection

Hi All,

I am trying to get a set of nodes that is really an intersection
and would appreciate some ideas for a solution.

What I need is the set of Matrix/Role nodes,
  that contains all of Roles for Items
  where $player is in at least one of the Roles for that Item.

For example, if I have a variable $player = '53', I
should get the set of Roles where roleID = {W,X,Y}, because
53 is in W and Y, and although 53 is not in X, that Role
is in at least one Item that also has roles W and Y. Also,
53 is in Role Z, but that Role does not belong to any Item so it is not
included.

I have a solution that works, but I was wondering if there is a simpler
way to express this.

<xsl:variable name="player" select="53"/>
<xsl:variable name="matrix" select="document('matrix.xml')"/>
<xsl:variable name="playerroles"
select="$matrix/Matrix/Role[PlayerLink/@player=$player]"/>
<xsl:variable name="matrixroles"
select="$matrix/Matrix/Role[@roleID=$matrix/Matrix/Item/RoleLink/@iRoleID[..
/../RoleLink/@iRoleID=$playerroles/@roleID]]"/>

<Matrix>
  <Role roleID="W">
    <PlayerLink player="1"/>
    <PlayerLink player="3"/>
    <PlayerLink player="6"/>
    <PlayerLink player="53"/>
  </Role>
  <Role roleID="X">
    <PlayerLink player="1"/>
    <PlayerLink player="3"/>
  </Role>
  <Role roleID="Y">
    <PlayerLink player="1"/>
    <PlayerLink player="3"/>
    <PlayerLink player="51"/>
    <PlayerLink player="53"/>
  </Role>
  <Role roleID="Z">
    <PlayerLink player="3"/>
    <PlayerLink player="53"/>
  </Role>

  <Item iID="123">
    <RoleLink iRoleID="W"/>
    <RoleLink iRoleID="X"/>
    <RoleLink iRoleID="Y"/>
  </Item>

  <Item iID="456">
    <RoleLink iRoleID="X"/>
    <RoleLink iRoleID="Y"/>
  </Item>

  <Item iID="789">
    <RoleLink kgRoleID="Y"/>
  </Item>
</Matrix>

Thanks very much,
Leona Slepetis
lrs@xxxxxxxxxxxx




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