Document analysis method and apparatus

A document comparison system for comparing a first document with a second document and a third document, the first document, the second document, and the third document being natural language documents, the first document having at least a first section comprising a plurality of first document entities, the second document comprising a plurality of second document entities, and the third document comprising a plurality of third document entities;

• the document comparison system comprising a processor and a memory device;
• wherein the processor is configured to:
• identify and extract the first document entities in the first section of the first document and determine a first framework in the form of a first directed graph having a rooted base node corresponding to the first document entity having a highest order, the first framework defining one or more first entity dependency between the first document entities, each first entity dependency defining a relationship between two of the first document entities;
• identify and extract the second document entities in the second document and determine a second framework in the form of a second directed graph, the second framework defining one or more second entity dependency between the second document entities, each second entity dependency defining a relationship between two of the second document entities;
• identify and extract the third document entities in the third document and determine a third framework in the form of a third directed graph, the third framework defining one or more third entity dependency between the third document entities, each third entity dependency defining a relationship between two of the third document entities;
• compare the first and second frameworks to assess a correlation between the first document entities and the second document entities, the comparison of the first and second frameworks comprises comparing the first entity dependencies between the first document entities in the first framework with the second entity dependencies between corresponding second document entities in the second framework;
• and
• compare the first and third frameworks to assess a correlation between the first document entities and the third document entities, the comparison of the first and third frameworks comprises comparing the first entity dependencies between the first document entities in the first framework with the third entity dependencies between corresponding third document entities in the third framework;
• wherein the first document is a patent document and the first section comprises or consists of one or more first patent claims, each first document entity being a first claim entity, the processor being configured to generate a report identifying one or more first claim entity together with an extract from the second document identified as being relevant to the first claim entity, and identifying one or more first claim entity together with an extract from the third document identified as being relevant to the first claim entity.