Changes between Version 3 and Version 4 of DevWikiEmptyGeometry

Timestamp:

Oct 6, 2009, 10:06:08 AM (15 years ago)

Author:

chodgson

Comment:

—

DevWikiEmptyGeometry

@@ -19 +19 @@
 It might make sense to try to maintain the geometric truisms when specifying the semantics around ''empty'' - ie. things like:
 
-* intersects( A, B ) => !disjoint( A, B )
-* A == B => intersects( A, B )
-* contains( A, B ) && contains( B, A ) => A == B
+ * intersects( A, B ) => !disjoint( A, B )
+ * A == B => intersects( A, B )
+ * contains( A, B ) && contains( B, A ) => A == B
 
 If we don't maintain these we will probably need to complicate logical comparisons with special cases for ''empty'' - it may be the case that this is necessary, but it would be nice if it just 'came out in the wash'.
@@ -27 +27 @@
 This suggests to me that perhaps:
 
-* ST_Intersects( empty, empty ) == TRUE
-* ST_Disjoint( empty, empty ) == FALSE
-* ST_Distance( empty, empty) == 0
-* ST_DWithin( empty, empty, tolerance) == true
+ * ST_Intersects( empty, empty ) == TRUE
+ * ST_Disjoint( empty, empty ) == FALSE
+ * ST_Distance( empty, empty) == 0
+ * ST_DWithin( empty, empty, tolerance) == true