Circumscription (logic) - Revision history

Karl Jones at 11:58, 12 April 2016

2016-04-12T11:58:14Z

Karl Jones at 14:56, 10 March 2016

2016-03-10T14:56:06Z

Karl Jones at 14:53, 10 March 2016

2016-03-10T14:53:48Z

Karl Jones: Created page with "'''Circumscription''' is a non-monotonic logic created by John McCarthy to formalize the common sense assumption that things are as..."

2016-03-10T14:46:16Z

Created page with "'''Circumscription''' is a non-monotonic logic created by John McCarthy to formalize the common sense assumption that things are as..."

New page

'''Circumscription''' is a [[non-monotonic logic]] created by [[John McCarthy (computer scientist)|John McCarthy]] to formalize the common sense assumption that things are as expected unless otherwise specified.

== Description ==

Circumscription was later used by McCarthy in an attempt to solve the [[frame problem]].

To implement circumscription in his initial formulation, McCarthy augmented first-order logic to allow the minimization of the extension of some predicates, where the extension of a predicate is the set of tuples of values the predicate is true on. This minimization is similar to the closed world assumption that what is not known to be true is false.

== Original problem ==

=== Missionaries and cannibals ===

The original problem considered by McCarthy was that of missionaries and cannibals:

* There are three missionaries and three cannibals on one bank of a river
* They have to cross the river using a boat that can only take two
** With the additional constraint that cannibals must never outnumber the missionaries on either bank, as otherwise the missionaries would be killed

=== Excluding conditions that are not explicitly stated ==

The problem considered by McCarthy was not that of finding a sequence of steps to reach the goal (the article on the missionaries and cannibals problem contains one such solution), but rather that of excluding conditions that are not explicitly stated.

== See also ==

* [[John McCarthy (computer scientist)]]
* [[Logic]]

== External links ==

* [https://en.wikipedia.org/wiki/Circumscription_(logic) Circumscription (logic)] @ Wikipedia

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	* [https://en.wikipedia.org/wiki/Circumscription_(logic) Circumscription (logic)] @ Wikipedia		* [https://en.wikipedia.org/wiki/Circumscription_(logic) Circumscription (logic)] @ Wikipedia
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 == Original problem ==
-=== Missionaries and cannibals ===
+The original problem considered by McCarthy was [[Missionaries and cannibals problem|missionaries and cannibals]]:
-The original problem considered by McCarthy was [[missionaries and cannibals]]:
+=== Problem statement ===
 * There are three missionaries and three cannibals on one bank of a river

@@ Line 11: / Line 11: @@
 === Missionaries and cannibals ===
-The original problem considered by McCarthy was that of missionaries and cannibals:
+The original problem considered by McCarthy was [[missionaries and cannibals]]:
 * There are three missionaries and three cannibals on one bank of a river
@@ Line 17: / Line 17: @@
 ** With the additional constraint that cannibals must never outnumber the missionaries on either bank, as otherwise the missionaries would be killed
-=== Excluding conditions that are not explicitly stated ==
+=== Excluding conditions that are not explicitly stated ===
 The problem considered by McCarthy was not that of finding a sequence of steps to reach the goal (the article on the missionaries and cannibals problem contains one such solution), but rather that of excluding conditions that are not explicitly stated.
@@ Line 25: / Line 25: @@
 * [[John McCarthy (computer scientist)]]
 * [[Logic]]
 ==  External links ==
 * [https://en.wikipedia.org/wiki/Circumscription_(logic) Circumscription (logic)] @ Wikipedia