Vulcan/SystemPrototype

Overview

The prototype is designed to work on three questions. We want the system to output the following:

• Score for the input proposition.

• New facts inferred.

• Facts and rules used in scoring.

Status

• Ran Tuffy on three example questions. It failed on one question.

• Hand generated the input evidence for the propositions (one correct and one incorrect) for three questions.
• Hand generated the MLN rules based on Stephen's human-readable rules.The MLN rules can be found here.
• Ran Tuffy to obtain the inference probabilities on the propositions.
• The system also outputs:

• All inferred facts along with their probabilities.
• All rules that are reachable from the query fact. i.e., Clauses in the MLN that are relevant to the inference of the query fact.

• Does it work?

• Tuffy gets it right for 2 out of 3 questions. i.e., it assigns higher probabilities for the correct proposition.
• Facts inferred by larger number of steps have a lower score compared to those inferred by a smaller number of steps.

• Why does it fail on the one question?

• The system fails on the iron nail example.
• Both "iron nail" and "plastic cup" get same high probability score (0.94). Don't know why this is happening..
• Based on manual inspection the plastic cup proposition should not get any score at all. Could be a bug in the way I codified the rules, or my interpretation of the MLN syntax is incorrect, or there is a genuine derivation that I somehow miss. Will dig in when I come back.

• What diagnostics do we NOT have?

• Connections between the clauses in the MLN.
• A reconstruction/visualization of the MLN network. Working with Tuffy developers on this.

• What next?

• Figure out why iron nail fails.
• Use automatically found evidence i.e., actual open ie tuples instead of hand-generated evidence.
• Figure out what mismatches exist between required and available knowledge.
• Improve diagnostics output.

• What does this exercise suggest?

• Need to figure out how the weights on the MLN rules and evidence are use. [I assigned them arbitrarily for this round.]
• Use predicates with small arity. For example, avoid writing rules entire nested tuples as predicates.
• The only reason we'd need a nested tuple is for the purpose of computing the score. For now we can compute this from the score of its components: Score(nested_tuple) = Score(top tuple) * Score (nested).