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[thelizardreborn]

I am using prolog to act as a database. My facts are all of the structure relation(Name,Type,Weight), with weight being floats.

I want to write a rule and query to write all relations with a weight greater than an input weight to the screen. I can get it to write one, here is what I have so far.

relation(itemA,type1,1.0).
relation(itemB,type3,16.0).
relation(itemC,type2,23.0).

weighOver(Weight):-
relation(Name,_,X),X>Weight,write(Name).

I might add that I am a beginner to Prolog, as well as any other non-procedural language, so I am having to rework how I approach problems. If I have to scrap what I have so far and set things up a different way, that's ok.

Thanks in advance!

 

[surfbluedog]

You will need to use a grouping predicate such as setof/3 like this:

setof(Name/Type/X, relation(Name,Type,X), Set),

where Set would be the List of all possible combinations. However I am not too sure how to filter out those possibilities where X is less than the weight specified