Knowledge base construction

A knowledge base construction system for updating a probabilistic knowledge base with a probabilistic generative model, the system comprising:

• a processor;
• and
• a memory storing the probabilistic generative model, an inference component, and a source tracker,
• the probabilistic knowledge base storing prior probability distributions of variables of the probabilistic generative model, the prior probability distributions representing likelihoods of particular values of the variables, and
• the inference component comprising computer executable instructions that upon execution by the processor:
• generate inference results using an inference algorithm that executes on the probabilistic generative model with unlabeled training data as input to the inference algorithm:
• in a forward direction resulting in observed formatted data and a posterior distribution being generated, the posterior distribution representing a likelihood of possible inference results across a document corpus given a particular query, being approximated by applying heuristics, and converted into a plurality of search queries executed across the document corpus resulting in an observed variable of the probabilistic generative model being populated, and
• in a reverse direction whereby the formatted data is observed and an unobserved variable of the probabilistic generative model is inferred;
• and
• update the prior probability distributions stored in the probabilistic knowledge base using a portion of the inference results, and
• the source tracker configured to determine source tracking information of the observed formatted data, the source tracking information comprising, for individual observations from the observed formatted data, security information of the observation,
• wherein the source tracker is configured to store the source tracking information in the probabilistic knowledge base such that other applications are able to retrieve the source tracking information by querying the probabilistic knowledge base,
• wherein the source tracker is configured to determine that an inferred fact has a single restricted source based on the source tracking information, and apply the same restriction to a query to the probabilistic knowledge base retrieving that inferred fact based on the determining.