[postgis-devel] Positional Operators

[Joel da Silva]

Dear friends,
I have a geographical database  in the PostreSQL 8.1
I have realized some test with positional operators in the postgis
e.g.:
 for two geographical features (A and B), we have the following positional
operators:

completely at-left     A << B
completely at-right   A >> B
 at-left or overlaps at-left  A  &<  B
 at-right or overlaps at-right  A  &>  B

completely above A |>> B
completely below A |<< B
above or overlaps above A  |&> B
below or overlaps below A  &<| B


North-West       A |>> B AND A << B
North-Est         A |>> B AND A >> B
South-West        A <<| B AND A << B
South-Est         A <<| B AND A >> B


but, how I can to express the  North-of, South-of,  Est-of  and West-of
positional   operators?

somebody can  help me
thanks for your attention
best regards
Joel
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