In EBNF, parentheses are used for

Non-linear substitution for encoding messages use a code word of length n² that is put into a(n)___

A connected acyclic graph is also called a

Given a graph G = (V, E), and we remove one or more vertices and all their associated edges, the resulting subgraph is called a(n) ____ subgraph on the remaining vertices.

ROT13(b) = 

Whenever a * a = a we say that a is 

Consider the graph G = This is called a __ graph

Which of the following are posets

Once we introduce positional labelling to the idea of a tree,  this becomes a(n) ___ under isomorphism

When encoding is done by replacing each letter with a different one this is called cypher by