Methods for handling uncertainty Default or nonmonotonic logic: Assume my car does not have a flat tire Assume A25 works unless contradicted by evidence Issues:What assumptions are reasonable?How to handle contradiction? ● Rules with fudge factors: ● -A251-0.3 get there on time Sprinkler0.99 WetGrass -VetGrass→o.7Rain Issues:Problems with combination,e.g.,Sprinkler causes Rain??Methods for handling uncertainty • Default or nonmonotonic logic: • – Assume my car does not have a flat tire – – Assume A25 works unless contradicted by evidence • Issues: What assumptions are reasonable? How to handle contradiction? • • Rules with fudge factors: • – A25 |→0.3 get there on time – – Sprinkler |→ 0.99 WetGrass – – WetGrass |→ 0.7 Rain • Issues: Problems with combination, e.g., Sprinkler causes Rain?? •