NPartitionPairs {TreeTools}

Distributions of tips consistent with a partition pair

Description

NPartitionPairs() calculates the number of terminal arrangements matching a specified configuration of two splits.

Usage

NPartitionPairs(configuration)

Arguments

configuration

Integer vector of length four specifying the number of terminals that occur in both (1) splits A1 and A2; (2) splits A1 and B2; (3) splits B1 and A2; (4) splits B1 and B2.

Details

Consider splits that divide eight terminals, labelled A to H.

Bipartition 1:	ABCD:EFGH	A1 = ABCD	B1 = EFGH
Bipartition 2:	ABE:CDFGH	A2 = ABE	B2 = CDFGH

This can be represented by an association matrix:

	A2	B2
A1	AB	C
B1	E	FGH

The cells in this matrix contain 2, 1, 1 and 3 terminals respectively; this four-element vector (c(2, 1, 1, 3)) is the configuration implied by this pair of bipartition splits.

Value

The number of ways to distribute sum(configuration) taxa according to the specified pattern.

Author(s)

Martin R. Smith ([e-mail])

Examples

NPartitionPairs(c(2, 1, 1, 3))