1. An automatic rule generation system, comprising: a hardware computer that executes a computer program that implements the automatic rule generation system, the computer program including a rule generation module, a rule relaxation module, a rule testing module, an information extraction module, and a candidate suggestion module, wherein: the rule generation module receives a sample and generates a rule from the sample; the rule relaxation module generates a relaxed rule from the rule; the rule testing module generates a reverse index from a corpus, applies the relaxed rule to the reverse index to determine a superset of documents from the corpus that satisfy the relaxed rule as compared to a set of documents that satisfy the rules, and generates text segments from the superset of documents; the information extraction module generates modified text segments from the relaxed rule and the text segments; and the candidate suggestion module performs a candidate generation process using the modified text segments, wherein: if the candidate generation process generates no candidates from the modified text segments, the candidate suggestion module signals the rule relaxation module to generate a further relaxed rule to use as the relaxed rule, and if the candidate generation process generates a candidate from the modified text segments, the candidate suggestion module provides the candidate as an additional sample for the automatic rule generation system to generate another rule to use as the rule.