PPT Slide

A RECURSIVE PROLOG PROGRAM FOR FACTORIAL

factorial( 0 , 1 ) .

factorial( N , ANS ) : -

N1 is N - 1 ,

factorial( N1 , ANS2 ) ,

ANS is N * ANS2 .

| ? - factorial( 3 , X ) .

N11 2

factorial( 2 , ANS21 )

N12 1

factorial( 1 , ANS22 )

N13 0

factorial( 0 , ANS23 )

factorial( 0 , 1 )

ANS3 1 * 1 = 1

ANS2 2 * 1 = 2

ANS1 3 * 2 = 6

X = 6

What happens if you now type ‘; ’ ?

bound to ANS1

bound to ANS2

bound to ANS3

P.26

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