# Backtracking issue on fail

**URL:** <https://swi-prolog.discourse.group/t/backtracking-issue-on-fail/2921>\
**Category:** Help!\
**Created:** [September 12, 2020, 4:31am UTC](https://swi-prolog.discourse.group/t/backtracking-issue-on-fail/2921 "2020-09-12T04:31:56Z")\
**Posts on this page:** 1\
**Showing post:** 10

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**Author:** ![EricGT](https://avatars.discourse-cdn.com/v4/letter/e/f1d935/32.png) [@EricGT](https://swi-prolog.discourse.group/u/EricGT)\
**Post date:** [September 12, 2020, 10:10am UTC](https://swi-prolog.discourse.group/t/backtracking-issue-on-fail/2921/10 "2020-09-12T10:10:08Z")

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> [@moraneus](#):
>
> The main reason I don’t give the whole problem, because it’s not so defined, due to the fact I create them and chose how to implement the way to solve them.

Have you seen: [Useful Prolog references](https://swi-prolog.discourse.group/t/useful-prolog-references/1089)  
There are a few excellent and free books listed. You really should learn from a book or site such as Learn Prolog Now! instead of making up your own problems to learn. But once you know the basics, I always suggest that real world problems will help you learn more than a book.

While the syntax is slightly different you might find this site of use.

[Prolog Visualizer](http://www.cdglabs.org/prolog/#/)

I note it because:

1. It might be of help to you. I know when I was learning unification it would have helped me.
2. I am curious to know if someone learning Prolog on their own finds the site of use and what problems they have with the site. The site has a few warts and with some enhancements/changes it could be very effective for new users.

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