def get_emissions_probability(label_matches, given_tag, given_word, tag_counts):
	"""Calculates the emissions probability of associating a given
	tag and word by the following formula:
	emissions_probability = (count of word associated with tag) / (count of tag)
	"""
	lookup_tuple = (given_word, given_tag)
	word_tag_frequency = label_matches.get(lookup_tuple, 0)
	tag_frequency = tag_counts[given_tag]
	if tag_frequency == 0:
		emissions_probability = 0
	else:
		emissions_probability = float(word_tag_frequency)/float(tag_frequency)
	return emissions_probability