Growth or movement of a plant or animal toward or away from an external stimulus, such as light, heat, or gravity. tropism. the tendency of a plant, animal, or part to move or turn in response to an external stimulus, as sunlight or temperature. â tropistic, adj.
The definition of a graph is a diagram showing the relationships between two or more things. An example of graph is a pie chart. Graph is defined as to create a diagram that shows a relationship between two or more things. An example of graph is to create a series of bars on graphing paper.
A tree is a mathematical structure that can be viewed as either a graph or as a data structure. The two views are equivalent, since a tree data structure contains not only a set of elements, but also connections between elements, giving a tree graph. Trees were first studied by Cayley (1857). McKay maintains a database of trees up to 18 vertices, and Royle maintains one up to 20 vertices.