4. Let’s define three events: 1. A as “draw 47 resistor 2. B as “draw” a resistor with 5% 3. C as “draw” a “100 resistor P(A) = P(47 ) = 44/100 P(B) = P(5%) = 62/100 P(C) = P(100 ) = 32 /100 The joint probabilities are: P(A B) = P(47 5%) = 28/100 P(A C) = P(47 100 ) = 0 P(B C) = P(5% 100 ) = 24/100 I f we use them the cond. prob. : Tolerance Resistance ( ) 5% 10% Total 22- 10 14 24 47- 28 26 44 100- 24 8 32 Total: 62 38 100
5.
6.
7.
8.
9. User Information Need Documents Document Representation Query Representation How to match? In traditional IR systems, matching between each document and query is attempted in a semantically imprecise space of index terms. Probabilities provide a principled foundation for uncertain reasoning. Can we use probabilities to quantify our uncertainties? Uncertain guess of whether document has relevant content Understanding of user need is uncertain
10.
11.
12.
13.
14. Let x be a document in the collection. Let R represent relevance of a document w.r.t. given (fixed) query and let NR represent non-relevance. p( x|R ), p( x|NR ) - probability that if a relevant (non-relevant) document is retrieved, it is x . Need to find p( R|x) - probability that a document x is relevant. p( R) ,p( NR ) - prior probability of retrieving a (non) relevant document R={0,1} vs. NR/R
15.
16.
17.
18.
19.
20.
21.
22.
23.
24. All matching terms Non-matching query terms All matching terms All query terms
25.
26.
27.
28.
29.
30.
31.
32.
33.
34. Gloom (g) Finals (f) No Sleep (n) Triple Latte (t) Project Due (d)
35.
36.
37. I - goal node Document Network Query Network Large, but Compute once for each document collection Small, compute once for every query d1 d n d2 t1 t2 t n r1 r2 r3 r k d i - documents t i - document representations r i - “concepts” I q2 q1 c m c2 c1 c i - query concepts q i - high-level concepts
38.
39. d 1 d 2 r 1 r 3 c 1 c 3 q 1 q 2 i r 2 c 2 Document Network Query Network Documents Terms/Concepts Concepts Query operators ( AND/OR/NOT ) Information need
40.
41. Hamlet Macbeth reason double reason two OR NOT User query trouble trouble Document Network Query Network