|WikiProject Mathematics||(Rated Start-class, Mid-priority)|
The examples are quite good, but there's no reference to the formal Tarski notion of a structure for a language as a universe together with interpretations for the relation, function, and constant symbols. I would be somewhat tempted to start a new page called "Structure (mathematical logic)" or some such, but the existing page has considerable math-logic content, so that might be excessive duplication. Suggestions welcome. --Trovatore 28 June 2005 18:48 (UTC)
- I think they should be separate articles. I disagree with your statement that the current article has considerable mathematical-logic content. —msh210 03:47, 8 September 2005 (UTC)
So I now see that the concept I have in mind is treated on the Model theory page, and there's a link to it on the article page. I don't think that really covers the issue, though. Every model is a structure, and every structure is a model of some theory (say, the theory of that structure). Nevertheless "model" and "structure" are not really synonymous. It's a question of emphasis: When you speak of a model, you generally have in mind some fixed theory that it's a model of; when you speak of a structure, you may not. --Trovatore 28 June 2005 18:56 (UTC)
Directions for expansion
- Structures are associated with symmetry groups as per Kleinian geometry, the importance of which in modern mathematics is still vastly underexplained in WP.
- Joyal's category theory approach gives a beautiful and powerful notion of combinatorial structure, sometimes called structors or combinatorial species (despite the second name, these are functors), which can and should serve as the basis for an undergraduate textbook (I have prepared extensive notes for such a book), but for now we have only the monograph
- Bergeron, F.; Labelle, G.; and Leroux, P. (1998). Combinatorial species and tree-like structures. Cambridge: Cambridge University Press. ISBN 0-521-57323-8.
- the Joyal cycle index is an important extension of the well known Polya cycle index, which is related to vast area of problems in enumerative combinatorics; see
- Cameron, Peter J. Permutation Groups. Cambridge: Cambridge University Press. ISBN 0-521-65378-9.
- Fraīssé theory, random graph, first order models of relational structures as per Cameron's book.
---CH 02:59, 12 August 2006 (UTC)
- I've got an idea, too (actually, it's more of a gripe of sorts:) why doesn't this article state its relationship with the article on structures in mathematical logic more explicitly and clearly?
- Where does it link to it? Firefox "find" doesn't find it. --Trovatore (talk) 19:42, 19 August 2009 (UTC)