Software Testing Methodologies Dichotomies

An interior point (on the screen image) is a point in the domain such that all points within an arbitarily small distance (called an epsilon neighborhood) are also in the domain
Epsilon neighborhood is a small space in the domain where a set of all points lie at some specific distance between them.

Domain Bugs and How to Test for Them

 It is one which is within an epsilon neighborhood there are points both in the domain and not in the domain

It is point which does not lie between any two other arbitrary but distinct points of a (convex) domain

An on point is a point on the boundary
If the domain boundary is closed, an off point is a point near the boundary but in the adjacent domain
If the boundary is open, an off point is a point near the boundary but in the domain being tested, as displayed on the screen. We can remember this by the acronym COOOOI: Closed Off Outside Open Off Inside

The display on the screen image shows genetic domain bugs: Closure bug, shifted boundaries, titled boundaries, extra boundary and missing boundary

A new boundary (dotted line) has been added resulting a domain bug

Boundary is missing (dotted line)