Recursive search in PROLOG

[@vyhuynh7230]

super easy to understand and follow! Thank you!!

[@techdose4u]

Welcome :)

[@isharathilina]

best explain, thank you..

[@chandrachurmukherjeejucse5816]

Goated Lectures

[@Huda-dq9tm]

Right so, I tried writing the same code and it showed an error that essentially meant that I was trying to overwrite the already defined member predicate. The error went away when I changed the name of the predicate to ismember.

[@techdose4u]

Hmm.... But it ran on my system!!

[@Huda-dq9tm]

@@techdose4u Guess our version is different.

[@varunkumar7237]

This is same as list membership right?

[@_DikshaBhise]

thank you

[@techdose4u]

Welcome 😀

[@pradyumanagrawal6089]

Can you explain how the "member" function works when there are two 'harry' in the list with the stack implementation of function?

[@keerthithejas.c.9098]

Hi,
First of all, your videos are great and thank you for these amazing videos. You are doing a great job. I am trying to understand how the search tree looks like while backtracking during recursion and I am kind of lost.
Say for Example the below lines of code, removes all the occurrences of an element from a list :
remove_all(_, [], []).
remove_all(El, [El|Tail], Tail2):-
remove_all(El, Tail, Tail2).
remove_all(El, [Head|Tail], [Head|Tail2]):-
not(El = Head),
remove_all(El, Tail, Tail2).
Now I query the following ?- remove_all( 2, [1,4,2,3,5,2,7,2], X). I used the online SWISH Prolog to execute it with the trace and I got the following tree
Call:remove_all(2, [1, 4, 2, 3, 5, 2, 7, 2], _4896)
Call:not(2=1)
Exit:not('10758ac0-dc91-4335-a0d8-48b7b11776c0' : (2=1))
Call:remove_all(2, [4, 2, 3, 5, 2, 7, 2], _5128)
Call:not(2=4)
Exit:not('10758ac0-dc91-4335-a0d8-48b7b11776c0' : (2=4))
Call:remove_all(2, [2, 3, 5, 2, 7, 2], _5146)
Call:remove_all(2, [3, 5, 2, 7, 2], _5146)
Call:not(2=3)
Exit:not('10758ac0-dc91-4335-a0d8-48b7b11776c0' : (2=3))
Call:remove_all(2, [5, 2, 7, 2], _5164)
Call:not(2=5)
Exit:not('10758ac0-dc91-4335-a0d8-48b7b11776c0' : (2=5))
Call:remove_all(2, [2, 7, 2], _5182)
Call:remove_all(2, [7, 2], _5182)
Call:not(2=7)
Exit:not('10758ac0-dc91-4335-a0d8-48b7b11776c0' : (2=7))
Call:remove_all(2, [2], _5200)
Call:remove_all(2, [], _5200)
Exit:remove_all(2, [], [])
Exit:remove_all(2, [2], [])
Exit:remove_all(2, [7, 2], [7])
Exit:remove_all(2, [2, 7, 2], [7])
Exit:remove_all(2, [5, 2, 7, 2], [5, 7])
Exit:remove_all(2, [3, 5, 2, 7, 2], [3, 5, 7])
Exit:remove_all(2, [2, 3, 5, 2, 7, 2], [3, 5, 7])
Exit:remove_all(2, [4, 2, 3, 5, 2, 7, 2], [4, 3, 5, 7])
Exit:remove_all(2, [1, 4, 2, 3, 5, 2, 7, 2], [1, 4, 3, 5, 7])
X = [1, 4, 3, 5, 7]
What I am not able to understand is how the backtracking is happening in these lines of code
Exit:remove_all(2, [], [])
Exit:remove_all(2, [2], [])
Exit:remove_all(2, [7, 2], [7])
Exit:remove_all(2, [2, 7, 2], [7])
Exit:remove_all(2, [5, 2, 7, 2], [5, 7])
Exit:remove_all(2, [3, 5, 2, 7, 2], [3, 5, 7])
Exit:remove_all(2, [2, 3, 5, 2, 7, 2], [3, 5, 7])
Exit:remove_all(2, [4, 2, 3, 5, 2, 7, 2], [4, 3, 5, 7])
Exit:remove_all(2, [1, 4, 2, 3, 5, 2, 7, 2], [1, 4, 3, 5, 7])
How does the prolog interpreter perform recursion on this? Can you please explain.

[@techdose4u]

Actually i am not doing prolog from a very long time and so I am not able to help you in this. I wish I could but please take help from community or your friends.

[@keerthithejas.c.9098]

OK !! No Problem. Thank you :)

[@hudadhiaa]

hello I want a hill climbing code in prolog can you help me even if it is in the form of a pdf or url

[@kumarpurushottam6737]

It is saying , no permission to define imported_procrdure list:member/2. What does this mean bro

[@malekferhi5029]

it's the same content as the one in the video of element membership in a list ! ain't it ?

[@techdose4u]

You can say so. For element membership check as well, we did recursive search.

[@malekferhi5029]

@@techdose4u Nice job anyway (y) keep up the good work , waiting for the next videos

[@robertungureanu7016]

pay attention, dude. your friend has already made a video explaining the same exercise, and it only took him half the time😂😂

[@ittehadabdullah8221]

if your native is hindi please explain in hindi, it'll bring you more audience