[CLOSED] Implement generalized inverse for three arrow calculus

<a href="https://github.com/sebasguts"><img src="https://avatars.githubusercontent.com/u/1068084?v=3" align="left" width="96" height="96" hspace="10"></img></a> **Issue by [sebasguts](https://github.com/sebasguts)**
_Wednesday Sep 03, 2014 at 11:39 GMT_
_Originally opened as https://github.com/sebasguts/CAP/issues/1_

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