def lowest_common_ancestor_depth(c):
span1 = _to_span(c[<NUM_LIT:0>])<EOL>span2 = _to_span(c[<NUM_LIT:1>])<EOL>ancestor1 = np.array(span1.sentence.xpath.split("<STR_LIT:/>"))<EOL>ancestor2 = np.array(span2.sentence.xpath.split("<STR_LIT:/>"))<EOL>min_len = min(ancestor1.size, ancestor2.size)<EOL>return min_len - np.argmin(ancestor1[:min_len] == ancestor2[:min_len])<EOL>
Return the minimum distance between a binary-Mention Candidate to their
    lowest common ancestor.

    For example, if the tree looked like this::

        html
        ├──<div> Mention 1 </div>
        ├──table
        │    ├──tr
        │    │  └──<th> Mention 2 </th>

    we return 1, the distance from Mention 1 to the html root. Smaller values
    indicate that two Mentions are close structurally, while larger values
    indicate that two Mentions are spread far apart structurally in the
    document.

    :param c: The binary-Mention Candidate to evaluate
    :rtype: integer