Editing PatternQuery:Principles (section)

===A More Formal Description===
There are two basic data structures that the language is built upon. These are:
* '''Pattern'''. A pattern is simply an arbitrary set of atoms.
* '''Pattern Sequence'''. A sequence of patterns. In mathematical terms, can be understood as a "set of patterns" which is another way of saying "set of sets of atoms".

And on these data structures, there are three basic types of queries:
* '''Generator queries'''. Generator queries, as the name suggests, generate sequences of patterns from the original input. They are the tool that transforms the input molecule into a stream of patterns that can be later modified or combined. Examples of these queries include <code>[[PatternQuery:Language_Reference#Atoms | Atoms()]]</code>, <code>[[PatternQuery:Language_Reference#Residues | Residues()]]</code>, and <code>[[PatternQuery:Language_Reference#RegularMotifs | RegularMotifs()]]</code>.
* '''Modifier queries'''. These queries operate on individual patterns and modify them or throw them away. Examples include <code>[[PatternQuery:Language_Reference#AmbientAtoms | AmbientAtoms()]]</code>, <code>[[PatternQuery:Language_Reference#ConnectedResidues | ConnectedResidues()]]</code>, and <code>[[PatternQuery:Language_Reference#Filter | Filter()]]</code>.
* '''Combinator queries'''. Combinatorial queries take as input two or more sequence of patterns and combine them into a single new sequence that satisfies given criteria. Examples include <code>[[PatternQuery:Language_Reference#Or | Or()]]</code>, <code>[[PatternQuery:Language_Reference#Near | Near()]]</code>, and <code>[[PatternQuery:Language_Reference#Path | Path()]]</code>.