Talk:Discrete Mathematics/Functions and relations

Lots of material there, maybe enough for several "modules". Would it make sense to divide it up ? -- Karl Wick

I'd be against the idea, in my opinion. If someone's trying to study the material, it'd be a great deal more difficult jumping back and forth through linking to other modules. Anyway, this module's almost done, just going to cover Hasse diagrams and some questions/answers and I'm done with this bit, I think. Dysprosia 10:20, 5 Sep 2003 (UTC)

Confusion about Cartesian product definition of Function
I was reading the Other function notation section of this module and was a bit confused by the wording of the last sentence:

So using set notation, a function can be expressed as the Cartesian product of its domain and range.

Shouldn't that read a function can be expressed **as a subset of** the Cartesian product of its domain and range.? Otherwise, the function would be defined as F={(1,1),(1,4),(1,9),(2,1),(2,4),(2,9),(3,1),(3,4),(3,9)}.

Or perhaps my understanding of a Cartesian product is incorrect. Just wanted some clarification. Thank you.
 * This confuses me too. Tim J Tylor (talk) 11:06, 23 April 2008 (UTC)

I think there is a short coming in the discussions of functions nothing has been mentioned one to one function or generally the types of functions

OR or XOR in trichotomy
I just added an example in the Trichotomy section but I'd like to know if the or we have is a strict OR (XOR) or not. If it is then my example is incorrect (since sometimes both aRb and bRa hold).

Thanks for your help :)

how can we find the union,intersection,complement, difference of two sets named R & S?

New Introduction and other fixes
Hi, I've taken the liberty to add an introduction and some other (less major) fixes. I'd like to know what everyone thinks. --Brian C. Wells (discuss • contribs) 05:37, 22 May 2011 (UTC)

Weird Approvals of Property Changes
I just undid a change that removed "Transitive" as one of the properties of equality. Equality is transitive: a = b and b = c implies a = c. In fact, the transitive property is one of the three necessary properties of an equivalence relation, of which equality is the classic example.

I have also seen other examples changed to false answers, but what bothers me more than these erroneous edits by random IPs is that they are being approved by Wikibookians with the rights to do so. I'm fairly new here, so I don't know what Wikibookians' common problems are, but what's going on here? Are they just too busy to make a detailed review? Does nobody care what's right and wrong here? Or is there something else I'm missing? Thanks in advance. --Brian C. Wells (discuss • contribs) 09:07, 5 June 2012 (UTC)