MHB How to find the Domain , Range , matrix for the relation R

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To find the domain and range for the given relations, the first relation (a) has a domain and range of {1, 2, 3, 4, 8}, as it consists of pairs where each element is equal to itself. For the second relation (b), the domain is {1, 2, 3, 4, 6} and the range includes elements that are multiples of these domain values. A matrix representation can be constructed based on these relations, with a digraph illustrating the connections between elements. Understanding the definitions of domain, range, matrix, and digraph is crucial for solving these problems effectively.
zuhaira35
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can anyone help me ?
i have a homework and i did't find any answer for it

the question is

find the Domain , Range , matrix and the digraph for the relation R

a ) A = { 1,2,3,4,8 } = B , aRb if and only if a=b

b) A = { 1,2,3,4,6 } =B , aRb if and only if a multiple of b
 
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Hello zuhaira35 and welcome to MHB! :D

We ask that our users show their progress (work thus far or thoughts on how to begin) when posting questions. This way our helpers can see where you are stuck or may be going astray and will be able to post the best help possible without potentially making a suggestion which you have already tried, which would waste your time and that of the helper.

Can you post what you have done so far?
 
zuhaira35 said:
can anyone help me ?
i have a homework and i did't find any answer for it

the question is

find the Domain , Range , matrix and the digraph for the relation R
a ) A = { 1,2,3,4,8 } = B , aRb if and only if a=b
b) A = { 1,2,3,4,6 } =B , aRb if and only if a multiple of b
If I had to do a problem like this, the first thing I would do is look up the definition of words I did not know! Do you know what "domain", "range", "matrix", and "digraph" mean here? Do you know what a "relation" is? Do you understand exactly what the relations referred to in (a) and (b) are?

A "relation" between two sets, A and B, (they may be the same set as here) is a collection of ordered pairs with the first member of each pair from A and the second from B. In (a) you are told that "aRb if and only if a= b" so it is the collection {(1, 1), (2, 2), (3, 3), (4, 4), (8, 8)}. Now, what are the "domain" and "range"?
 
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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