core.logic

nominal unification misses after-the-fact fd constraints

Details

  • Type: Defect Defect
  • Status: Resolved Resolved
  • Priority: Major Major
  • Resolution: Completed
  • Affects Version/s: None
  • Fix Version/s: None
  • Component/s: None
  • Labels:
    None

Description

Related to http://dev.clojure.org/jira/browse/LOGIC-92, these two snippets both return (nom/tie 'a_0 1) instead of three results for 1, 2, 3.

(run* [q]
  (nom/fresh [a b c]
    (fresh [x y]
      (== (nom/tie b (nom/tie a x)) (nom/tie c q))
      (infd x (interval 1 3)))))

(run* [q]
  (nom/fresh [a b c]
    (fresh [x y]
      (infd y (interval 1 3))
      (== (nom/tie b (nom/tie a x)) (nom/tie c q))
      (== x y))))

Activity

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Nada Amin added a comment -

logic-98.diff fixes this by forcing all nom-related vars at once.

Do you have any ideas for separating the concern, so that force-ans doesn't need to know about ::nom?

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Nada Amin added a comment - logic-98.diff fixes this by forcing all nom-related vars at once. Do you have any ideas for separating the concern, so that force-ans doesn't need to know about ::nom?
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David Nolen added a comment -

Will need to think about this some more.

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David Nolen added a comment - Will need to think about this some more.
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Nada Amin added a comment -

Ouch! Here is a snippet that doesn't do the right thing, even with the patch:

(run* [q]
  (nom/fresh [a b c d]
    (fresh [x y z]
      (== (nom/tie b (nom/tie a x)) (nom/tie c z))
      (infd x (interval 1 3))
      (== (nom/tie d q) z))))

It returns only (1) instead of (1 2 3).

Show
Nada Amin added a comment - Ouch! Here is a snippet that doesn't do the right thing, even with the patch: 
(run* [q]
  (nom/fresh [a b c d]
    (fresh [x y z]
      (== (nom/tie b (nom/tie a x)) (nom/tie c z))
      (infd x (interval 1 3))
      (== (nom/tie d q) z))))
It returns only (1) instead of (1 2 3).
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Nada Amin added a comment -

logic-98-nominal.diff is a solution that works for all three test cases above by simply making core.logic.nominal aware of ::fd and updating the doms when appropriate.

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Nada Amin added a comment - logic-98-nominal.diff is a solution that works for all three test cases above by simply making core.logic.nominal aware of ::fd and updating the doms when appropriate.
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David Nolen added a comment -

fixed, http://github.com/clojure/core.logic/commit/ef27fa3ed2381f3ad4685d4bc59a298646a4febb

It would be nice if nominal didn't need to know about fd, as there will be other "enumerable" domains in the future. But this works great for now.

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David Nolen added a comment - fixed, http://github.com/clojure/core.logic/commit/ef27fa3ed2381f3ad4685d4bc59a298646a4febb It would be nice if nominal didn't need to know about fd, as there will be other "enumerable" domains in the future. But this works great for now.

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Dates

  • Created:
    Updated:
    Resolved:
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