=pod

=head2 Interval Matching

 .........A============B......... Search Range
 ...x--y..|............|......... (never match)
 .........|............|...x--y.. (never match)
 ......x--|--y.........|......... (1)
 ......x--|------------|---y..... (2)
 .........|...x-----y..|......... (3)
 .........|..........x-|----y.... (4)

=over 4

=item Intersection

A <lt>= y && B <gt>= x

matches examples 1,2,3,4

=item (item fully contained by search range)

A <lt>= x && B <gt>= y

matches example 3 only.

=item (item fully includes search range)

A <gt>= x && B <lt>= y

matches example 2 only.

=cut