def is_mention_subset(small_mention_text, large_mention_text):
    """
    Check if the smaller mention is a "subset" of the larger mention.
    We define "subset" in a very specific way:
    1. Subsequence:
       Example: Barack is a subset of Barack Obama,
                John Kelly is a subset of John Kelly Smith,
                Kelly Smith is a subset of John Kelly Smith, etc.
                And, Barack is a subset of Barack.
    2. The smaller string is equal to the larger string minus the words in the
        middle.
       Example: John Smith is a subset of John Jackson Smith.
    """
    small_mention_tokens = small_mention_text.split()
    large_mention_tokens = large_mention_text.split()
    if small_mention_text in large_mention_text:
        return True
    elif len(large_mention_tokens) > 2:
        if small_mention_tokens == \
                [large_mention_tokens[0], large_mention_tokens[-1]]:
            return True
    return False