Abscissa and ordinate a parametric equation. Used in this way, the abscissa can be thought of as a coordinate-geometry analog to the independent variable in a mathematical model or experiment (with any ordinates filling a role analogous to dependent variables). Abscissa and ordinate In mathematics, the abscissa (; plural "abscissae" or "abscissæ" or "abscissas") and the ordinate are respectively the first and second coordinate of a point in a coordinate system. The abscissa of a point is the signed measure of its projection on the primary axis, whose absolute value is the distance between the projection and the origin of the axis, and
Forbidden graph characterization family. Different families vary in the nature of what is "forbidden". In general, a structure "G" is a member of a family formula_1 if and only if a forbidden substructure is not contained in "G". The forbidden substructure might be one of: The set of structures that are forbidden from belonging to a given graph family can also be called an obstruction set for that family. Forbidden graph characterizations may be used in algorithms for testing whether a graph belongs to a given family. In many cases, it is possible to test in polynomial time whether a given graph contains