[postgis-users] Create common vertexes between shared polygon boundaries in PostGis?

[Nick Ves]

Given two polygon tables L1 (blue) and L2 (red) that  share a common
boundary but different vertexes how can one make the common boundary
identical (they should share the same vertexes) ?

 reference picture:  http://i.stack.imgur.com/11Eq6.png