source: tags/arb_5.1/HELP_SOURCE/oldhelp/trees.hlp

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#************* Title of helpfile !! and start of real helpfile ********
TITLE           Trees

OCCURRENCE      ARB_NT

DESCRIPTION     A tree consists of two types of 'nodes':

                - tips or terminal nodes: species

                        connected to exactly one father

                - inner nodes: hypothetical ancestors

                        connected to one father
                        (and in the binary case to two children).
                        A group_name may be assigned to an inner node; in this
                        case, the node and all its children become a group.
                        <ARB_NT/INFO_MODE/M>

                There are significant differences between
                phylogenetic trees and binary trees:

                phylogenetic trees                      binary trees:
                -------------------------------------------------------------------------
                unrooted                                rooted
                inner nodes have n children             all inner nodes have two children

                Since binary trees are much easier to handle, ARB converts
                phylogenetic trees to binary trees.