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# Function to intersect another polygon using OpenLayers

I wonder if someone here have a JavaScript function that when I draw a polygon I can see if I am drawing on another polygon?

like intersect… if polygon intersect say to me a alert…

using OpenLayers.

You can have a look at the intersection example of OpenLayers: http://dev.openlayers.org/examples/intersects.html

``for(var i=0; i``

## Topology

In mathematics, topology (from the Greek words τόπος , 'place, location', and λόγος , 'study') is concerned with the properties of a geometric object that are preserved under continuous deformations, such as stretching, twisting, crumpling, and bending that is, without closing holes, opening holes, tearing, gluing, or passing through itself.

A topological space is a set endowed with a structure, called a topology, which allows defining continuous deformation of subspaces, and, more generally, all kinds of continuity. Euclidean spaces, and, more generally, metric spaces are examples of a topological space, as any distance or metric defines a topology. The deformations that are considered in topology are homeomorphisms and homotopies. A property that is invariant under such deformations is a topological property. Basic examples of topological properties are: the dimension, which allows distinguishing between a line and a surface compactness, which allows distinguishing between a line and a circle connectedness, which allows distinguishing a circle from two non-intersecting circles.

The ideas underlying topology go back to Gottfried Leibniz, who in the 17th century envisioned the geometria situs and analysis situs. Leonhard Euler's Seven Bridges of Königsberg problem and polyhedron formula are arguably the field's first theorems. The term topology was introduced by Johann Benedict Listing in the 19th century, although it was not until the first decades of the 20th century that the idea of a topological space was developed.