[Haskell-beginners] Doing a DFS from scratch ....

[Ut Primum]

Hi Claudio,
I had a look at the code, and it looks that in dfs_search function, where
the comment says that "BACTRACKING is happening HERE" there is something
wrong (it looks neighbours are not all considered, because as you said
next_node returns only one neighbour).
I think that the definition of
dfs_search (x:xs) l_closed
is wrong. I'd start to write it from the beginning, instead of correcting
this code.

Cheers,
Ut

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Il giorno mer 21 ott 2020 alle ore 00:37 Claudio Cesar de Sa <
ccs1664 at gmail.com> ha scritto:

> Hi everyone
>
> Initially, I hope that this list is active yet.  For some days,
> I had been trying to do a Depth First Search on a graph from scratch
> following something very didactical (clear, elegant - legible, any worry
> about efficiency).
>
> This DFS keeps a boolean list to mark the nodes already visited and
> another with current or valid nodes ( the stack of DFS classic).
>
> The code is naive and well documented and is here:
>
> https://github.com/claudiosa/CCS/blob/master/haskell/dfs_graph.hs
> (excessively commented)
>
> but unfortunately, it is not working.  My guess is  that the problem
> starts on *new_node* function.  I am not sure if in DFS, when a current
> node gets a next neighbour to stack, it gets all the neighbours.
> In this code, it is getting one node per time.
>
> The functions next_node and one_node seem very non-sense. Could someone
> help me?
>
> Thanks in advance
>
>
>
> claudio
>
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