Changes

== Parsimony ==

== Parsimony ==

Parsimony means doing  something in the simplest and most economical way.  In the context of variant representation, this means representing a variant in as few nucleotides as possible.  Taking the example above, the MNP is represented superfluously for the first 3 representations and parsimoniously for the 4th representation.  When a variant has superfluous nucleotides on the left side, there is a need to left trim.  The concept is symmetric for right trimming.   

Parsimony means doing  something in the simplest and most economical way.  In the context of variant representation, this means representing a variant in as few nucleotides as possible.  Taking the example below, the Multi Nucleotide Polymorphism (MNP) is represented superfluously for the first 3 representations and parsimoniously for the 4th representation.  When a variant has superfluous nucleotides on the left side, there is a need to left trim.  The concept is symmetric for right trimming.   

[[Image:normalization_mnp.png|none|700px|This figure shows multiple representations of a MNP. The left shows 4 possible representations differentiated by color. The right shows the corresponding representation in VCF. The last representation represents the parsimonious representation of the MNP.]]  

[[Image:normalization_mnp.png|none|700px|This figure shows multiple representations of a MNP. The left shows 4 possible representations differentiated by color. The right shows the corresponding representation in VCF. The last representation represents the parsimonious representation of the MNP.]]