What is the formula for creating a set of paired elements?

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The discussion revolves around defining a set of paired elements using set theory and Zed notation. The user seeks a formula to express a set containing specific pairs, such as married couples or material types, rather than a Cartesian product. They explore the concept of bijections to represent these pairs, suggesting that a set of key-value pairs could be denoted as X↔Y. The user is interested in modeling relationships through set theory and logic, despite being new to the subject. Ultimately, they aim to clarify how to formally express these paired relationships in a set definition.
necro_ignis
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Hi all,

I'm trying to express a given requirement in a software system. I'm used to UML and UseCase specification, but I thought I would attempt to learn Zed Specification (which is based off logic, set theory., etc... so those topics too!)

Given two sets of data
e.g. in Zed notation

[X] ::= a|b|c|d
[Y]::= 1|2|3|4

or in Set Theory

X = {a,b,c,d}
Y = {1,2,3,4}

In set notation I am having difficulty trying to write down the formula for specifying a set containing a list of pairs made from X and Y. Note: Not a Cartesian Product.
So I'm looking for a Set definition for something like this:

MysterySet = {(a,1),(b,2),(c,3),(d,4)}
or a further example,
Material = {(chair,wood),(table,metal),(cup,clay)}

This is basically an analogy for a key-value pair.

Thanks very much.
 
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I can't decipher just what it is you are trying to do...
 
Hurkyl said:
I can't decipher just what it is you are trying to do...

Hi :smile:

I'm just trying to write a set definition for a set containing a list of paired values. Where each paired value is a single member of that set.

For example the set of all married couples Married = {(bob,jane),(fred,susan),(mike,sarah)} will have been built from the two sets: female={jane,susan,sarah} and male={bob,fred,mike}

So in a set definition how do I say something like:

each element in the set "Married" is a paired value from an enumerated one-to-one mapping between an element in the set male to the set female.

Hope that help! :biggrin: I could do this is a second programmatically but I have become extremely interested in modeling using set theory and logic, although it's something I've only just strated learning.

Thanks
 
After having done further research, it looks like a set of key-valued pairs might be (might be, being this is what I have thought up myself) represented as the set of all bijections as denoted X\leftrightarrowY.

So would I be right in saying (this is so sketchy and grasping at straws)
If I have a dom X = {1,2,3} and ran Y = {a,b,c} then a set S = {f:X\leftrightarrowY} would infact look like S={(a,1),(b,2),(c,3)}

P.S. Still getting used to the Latex function on this forum :rolleyes:

Thanks
 
I was reading documentation about the soundness and completeness of logic formal systems. Consider the following $$\vdash_S \phi$$ where ##S## is the proof-system making part the formal system and ##\phi## is a wff (well formed formula) of the formal language. Note the blank on left of the turnstile symbol ##\vdash_S##, as far as I can tell it actually represents the empty set. So what does it mean ? I guess it actually means ##\phi## is a theorem of the formal system, i.e. there is a...

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