Talk:Predicate (mathematical logic)

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Any chance of anyone explaining this so the average reader could get an understanding of what it means? Tyrenius 18:46, 24 October 2006 (UTC)

Follow the new external link for an explanation.

S Sepp 14:04, 26 October 2006 (UTC)

Thanks for the reference, but that's hardly an acceptable solution to a poor article. Hoping someone actually has this on their watch list and notices that the problem still exists. MJKazin (talk) 18:34, 23 April 2008 (UTC)


See Talk:Predicate (mathematics). --Abdull 11:04, 3 December 2007 (UTC)

See Talk: Predicate variable. Sae1962 (talk) 07:27, 2 March 2011 (UTC)

  • Don't merge. Cleanup instead. There's a lot of confusion between the articles on propositional logic, first-order logic, term algebra, model theory, type theory, philosophy, general mathematics, and semantics(?). All have similar-but-different notions of predicates, but differ sharply in the details. I tried to clean up this article to make this clear, but I believe it has a loooong way to go. linas (talk) 17:05, 9 June 2011 (UTC)

Atomic formula[edit]

The follwoing in the article does not accord with Atomic formula and is surely wrong

— Philogos (talk) 22:07, 16 June 2011 (UTC)

There were a lot of problems with the text, but I think I have removed most of them. — Carl (CBM · talk) 02:03, 17 June 2011 (UTC)


Thus seems confusing:

  • Informally, a predicate is a statement that may be true or false depending on the values of its variables.[citation needed] It can be thought of as an operator or function that returns a value that is either true or false.

better sruely would be

  • Informally, a predicate is an operator or function that returns a value that is either true or false. depending on the values of its variables.
I think it's better to say something like "a predicate can be represented by a function that ...". This avoids using the word "is" about the predicate. — Carl (CBM · talk) 02:40, 17 June 2011 (UTC)
Interesting. Then we have (a) predicate symbols(b) predicates (c) functions, and a predicate can be represented by a function. Eg
  • 'F' is a predicate symbol [type (a)]
  • under an intepretation it, 'F', can be associated with a predicate, egs. prime, even [type (b)]
  • the prime, even and green can be represented by functions (from numbers to {t,f}

That gives us three ontological classes. On the princile of Ackhams razor, would it not be simpler to say

  • under an intepretation 'F', can be associated with a predicate, egs. prime, even which are functions (from numbers to {t,f}

— Philogos (talk) 01:31, 18 June 2011 (UTC)

formal definition[edit]

The following in para formal definition do not provide formal definitions of the term predicate.

  • In propositional logic, atomic formulae are called propositional variables.
  • In first-order logic, an atomic formula consists of a predicate symbol applied to an appropriate number of terms.

The article is about predicates not predicate symbols— Philogos (talk) 02:29, 17 June 2011 (UTC)

Indeed. — Carl (CBM · talk) 02:39, 17 June 2011 (UTC)
So the items quoted do not provide a formal definition of the term predicate. (not to be conmsuded with the term predicate symbol or predicate letter

"atomic formula and an atomic sentence" ??? I was reading the article, and it was reasonable to follow, until I came across mention of "atomic formula and an atomic sentence". I've no idea what these are. No clue is given. What is this going on about? — Preceding unsigned comment added by (talk) 10:46, 19 August 2011 (UTC)

Cleanup needed[edit]

In its current form, the article augments rather than reduces confusion. To begin with, proposition and predicate are mixed up. Simply put, using the notation of the article, P(x) is a proposition and P is a predicate. This is the most commonly (although not universally) used terminology. The article should be cleaned up to reflect this. Boute (talk) 07:06, 19 October 2015 (UTC)

Wrong assertion at "Simplified overview" section[edit]

  • RIGHT.  If t is an element of the set {x | P(x)}, then the statement P(t) is true.
  • WRONG.  Here, P(x) is referred to as the predicate, and x the subject of the proposition.

The x variable is not the subject (supposing a context of subjectpredicateobject). See this example:

A = {x | the square is a subclass of x} and see the set of elements here. So, the set A was defined by the use of x as object not as subject of the phrase (the predicate of the set),
A = {rectangle, rhombus, hypercube, cross-polytope, ...}

P(x) is a template function, as in "Hello %!" where the symbol % is a placeholder to be replaced to anything. Correcting the WRONG to RIGHT:

  • RIGHT.  Here, P(x) is referred to as the predicate, and x the placeholder of the proposition.
    Sometimes, P(x) is also called a (template in the role of) propositional function, as each choice of the placeholder x produces a proposition.

--Krauss (talk), 26 November 2017