Normal forms

Evaluation Order and Infinite Lists - slide 13 : 27

Normal forms

A normal form represents our intuition of the value of an expression

An expression is on normal form if it cannot be reduced further by use of beta and eta conversions

About normal forms
- Some expressions have no normal form
- Alpha conversions can be used infinitely, and as such they do not play any role in the formulation of a normal form
- A normal form is a particular simple expression, which is equivalent to the original expression, due to the application of the conversions (reductions)

An example of a Scheme expression without a normal form.

Scheme expressions - some of which are in normal form.

Is a normal form always unique?