Patterns and problems

I was reminded of patterns when I read E.O wilson's Letters to a Young Scientist that every form of life is an answer to a problem.

Here is a short list of patterns and problems they attempt to answer

Pattern	Problem
Singleton	Only one instance of an object
Strategy	Apply functionality only where needed - not the whole inheritance chain
	Avoid multiple switch statements
Observer	Loosely coupled way to notify
Template	force child classes to implement what they need (by making those methods abstract) , but follow the parents process
Factory Method	Method for subclasses to create correct class
	Works in tandem with strategy
Abstract Factory	Defer concrtete implementation for child classes
	Avoid multiple switch statements
	A way to have multiple versions of a class
Façade	Simplify gateway to single/multiple interfaces
Command	Loosely coupled way to execute a method
	good for Qeues