Arlington County has an extensive network of bicycle infrastructure, including 50 miles of shared-use off-street trails. These multi-use trails are generally 10 feet wide with a solid yellow line striped down the middle to separate users.
Constructive mathematics. Idea. Broadly speaking, constructive mathematics is mathematics done without the principle of excluded middle (or other principles, such as the full axiom of choice, that imply it).
A: A constructive force creates or builds something on the earth. For instance, volcanoes are built up by constructive tectonic plate movement. Destructive forces like tornadoes and tsunamis tear down or wear away parts of the earth.