17. A system comprising one or more computers and one or more storage devices storing instructions that when executed by the one or more computers cause the one or more computers to perform operations comprising: receiving one or more seed fact pairs, each seed fact pair associating a seed fact first phrase and a seed fact second phrase, wherein the seed fact first phrase is a seed fact subject and the seed fact second phrase is a piece of information; receiving a set of one or more candidate fact pairs, each candidate fact pair associating a candidate fact first phrase and a candidate fact second phrase, wherein the candidate fact first phrase is a candidate fact subject and the candidate fact second phrase is a piece of information; receiving similarity score data, wherein the similarity score data identifies, for each of a plurality of pairs of distributionally similar words, a respective similarity score between the distributionally similar words in the pair that defines how similar the distributionally similar words in the pair are; and calculating a similarity score for each candidate fact pair with respect to at least one seed fact pair, wherein the similarity scores represent measures of similarity between respective ones of the candidate fact pairs and the at least one seed fact pair, and wherein calculating the similarity score for each candidate fact pair comprises: determining a respective first similarity score for each word in the candidate fact first phrase that represents the similarity of the word to words from the seed fact first phrases from the at least one seed fact using the similarity score data, determining a respective second similarity score for each word in the candidate fact second phrase that represents the similarity of the word to words from the seed fact second phrases from the at least one seed fact using the similarity score data, and computing the similarity score for the candidate fact pair by combining the first and second similarity scores.
17. A system comprising one or more computers and one or more storage devices storing instructions that when executed by the one or more computers cause the one or more computers to perform operations comprising: receiving one or more seed fact pairs, each seed fact pair associating a seed fact first phrase and a seed fact second phrase, wherein the seed fact first phrase is a seed fact subject and the seed fact second phrase is a piece of information; receiving a set of one or more candidate fact pairs, each candidate fact pair associating a candidate fact first phrase and a candidate fact second phrase, wherein the candidate fact first phrase is a candidate fact subject and the candidate fact second phrase is a piece of information; receiving similarity score data, wherein the similarity score data identifies, for each of a plurality of pairs of distributionally similar words, a respective similarity score between the distributionally similar words in the pair that defines how similar the distributionally similar words in the pair are; and calculating a similarity score for each candidate fact pair with respect to at least one seed fact pair, wherein the similarity scores represent measures of similarity between respective ones of the candidate fact pairs and the at least one seed fact pair, and wherein calculating the similarity score for each candidate fact pair comprises: determining a respective first similarity score for each word in the candidate fact first phrase that represents the similarity of the word to words from the seed fact first phrases from the at least one seed fact using the similarity score data, determining a respective second similarity score for each word in the candidate fact second phrase that represents the similarity of the word to words from the seed fact second phrases from the at least one seed fact using the similarity score data, and computing the similarity score for the candidate fact pair by combining the first and second similarity scores. 18. The system of claim 17 , the operations further comprising ranking each candidate fact pair based on calculated similarity scores for each candidate fact pair.