# Maximum Agreement Subtree (of 2 Binary Trees)

**DOI:**https://doi.org/10.1007/978-3-642-27848-8_220-2

## Problem Definition

Consider two rooted trees *T*_{1} and *T*_{2} with *n* leaves each. The internal nodes of each tree have at least two children each. The leaves in each tree are labeled with the same set of labels, and further, no label occurs more than once in a particular tree. An *agreement subtree* of *T*_{1} and *T*_{2} is defined as follows. Let *L*_{1} be a subset of the leaves of *T*_{1} and let *L*_{2} be the subset of those leaves of *T*_{2} which have the same labels as leaves in *L*_{1}. The subtree of *T*_{1}*induced* by *L*_{1} is an agreement subtree of *T*_{1} and *T*_{2} if and only if it is *isomorphic* to the subtree of *T*_{2} induced by *L*_{2}. The maximum agreement subtree problem (henceforth called *MAST*) asks for the largest agreement subtree of *T*_{1} and *T*_{2}.

The terms *induced subtree* and *isomorphism* used above need to be defined. Intuitively, the subtree of *T* induced by a subset *L* of the leaves of *T* is the topological subtree of *T* restricted to the leaves in *L*, with branching information relevant to *L*preserved. More formally, for any two...

## Keywords

Isomorphism Tree agreement## Recommended Reading

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