def resolve_pos(token):
    """If necessary, add a field to the POS tag for UD mapping.
    Under Universal Dependencies, sometimes the same Unidic POS tag can
    be mapped differently depending on the literal token or its context
    in the sentence. This function adds information to the POS tag to
    resolve ambiguous mappings.
    """
    # TODO: This is a first take. The rules here are crude approximations.
    # For many of these, full dependencies are needed to properly resolve
    # PoS mappings.
    if token.pos == "連体詞,*,*,*":
        if re.match(r"[こそあど此其彼]の", token.surface):
            return token.pos + ",DET"
        if re.match(r"[こそあど此其彼]", token.surface):
            return token.pos + ",PRON"
        return token.pos + ",ADJ"
    return token.pos