Symbolic Reasoning Under Uncertainty

Predicate Logic:

So far we have used complete, consistent, and unchanging (monotonic) models of the world.

Reasoning involves manipulating a set of beliefs

Logics dealing with Uncertainty:

* nonmonotonic - allows deletion of statements

* probabilistic reasoning - likelihoods (Bayes often used in medical diagnosis)

* fuzzy logic - Zadeh - continuity (time and space)

* belief spaces -(each individual lives in own world)

Most probable choice: in the absence of information, we choose the most likely

Most dogs have tails

Most people like flowers

Deduction/induction/abduction

* distinctions *

Abduction: inference to the best explanation:

Not a proof! ... only plausible inference (Text calls it Explaining Away)

D is a collection of facts

H explains D (would, if true, explain D)

________________________________

Thus, H is correct

another way

Example:

if (drunk ?person) then (not (walk straight ?person))

(not (walk straight Jack))

thus, (drunk Jack)

abduction is a kind of default reasoning