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Factors influencing Forward and Backward chaining. Is the goal precisely known? Fan-in and Fan-out of rules. Rule Structure. R 1 : P 1 ^ P 2 ^ P 3 ^ . . . . . . ^ Pn Q 1 R 2 : P 1 ^ P 2 ^ P 3 ^ . . . . . . ^ Pn Q 2 .
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Factors influencing Forward and Backward chaining Is the goal precisely known? Fan-in and Fan-out of rules.
Rule Structure R1: P1 ^ P2 ^ P3 ^ . . . . . . ^ Pn Q1 R2: P1 ^ P2 ^ P3 ^ . . . . . . ^ PnQ2 . Rk : P1 ^ P2 ^ P3 ^ . . . . . . ^ PnQk P1P2 . Pn AND OR Q1 Q2. Qk
AND AND Forward chaining Mk P1 M2 P2 M1 Pk P1 P2 .. Pn Q1 Q1 • If Fan-out is less Forward chaining is preferable ?
S AND Important Data structure: AND-OR Graph D OR A OR B C Dn D3 A1 A2 D2 A3 An D1 B1 B2 B3 C2 C1 • Structure of AND-OR Graph decides the • direction of inferencing.