Mapping a: S -> T be so that any x ε S has one and only one y &#

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Discussion Overview

The discussion revolves around the concept of mappings from set S to set T, specifically focusing on the condition that each element x in S corresponds to exactly one element y in T. The scope includes definitions of functions and the nature of mappings in mathematics.

Discussion Character

  • Conceptual clarification, Debate/contested

Main Points Raised

  • One participant asserts that the property of having one and only one y for each x is the defining characteristic of a function from S to T.
  • Another participant questions whether this necessity is purely definitional.
  • A different viewpoint suggests that it is not necessary to restrict discussions to functions, as there are mappings that do not qualify as functions.
  • One participant acknowledges that they were referring specifically to functions and asks for clarification on the definitions of S and T.
  • A later reply emphasizes that if S and T are any sets and "mapping" is interpreted as "function," then the property holds true based on the definition of a function.

Areas of Agreement / Disagreement

Participants express differing views on whether the property of having one output for each input is necessary by definition or if it can be applied more broadly to other types of mappings. The discussion remains unresolved regarding the necessity of this property in different contexts.

Contextual Notes

There is ambiguity regarding the definitions of sets S and T, as well as the specific context in which the term "mapping" is used. This may affect the interpretation of the necessity of the property discussed.

Gear300
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mapping a: S --> T be so that any x ε S has one and only one y &#

What makes it necessary for any mapping a: S --> T be so that any x ε S has one and only one y ε T?
 
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That's the defining property of a being a function from S to T.
 


So it is necessary only by definition?
 


It is not necessary at all. One can talk about mappings that are not functions as well. What is the context of this question?
 


I see...what I was referring to were particular types of mappings (functions), right?
 


It might help if you told us exactly what you mean by "S" and "T"!

If you are referring to any sets S and T and by "mapping" you specifically meant "function", then yes, that is true simply because of the definition of "function".
 

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