Abstract: A computer-implemented method used for analyzing documents by an artificial intelligence system is disclosed herein. The method includes uploading at least one document via a frontend which stores the document in a database of the artificial intelligence system; preprocessing at least one document retrieved from the database by splitting the document into individual sentences and calculating a word vector for each sentence of the document; assessing each sentence using a categorization model of the artificial intelligence system by processing the calculated word vector representing the sentence to provide a categorization prediction result; and processing positive categorized sentences in order to calculate an opinion prediction result and a sub-categorization prediction result for each positive categorized sentence based on an opinion prediction model and based on a sub categorization model of the artificial intelligence system.