Additional library which depends on SSReflect (by my ad-lib coding).

(compatible with ssreflect-1.5 and coq-8.4pl4)

SSReflect を使って作ったライブラリ的なものを投入中．

digraph はこちらに統合される予定です．

Type of binary tree and some utility functions are defined.

And some properties are proved (in progress)

(will be written)

Types of tree and forest are defined by using mutual inductive definition.