Counting Subfields in F_p: Algebraic Result?

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Discussion Overview

The discussion revolves around counting the number of subfields in the prime field F_p, where p is a prime number. Participants explore whether this is a known algebraic result and the implications of field characteristics on subfields.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant questions how to count the number of subfields in F_p, suggesting it may be a known result in algebra.
  • Another participant asserts that F_p cannot have any proper subfields, implying that it is the smallest field of characteristic p.
  • A third participant agrees with the notion that there are no proper subfields, suggesting that the count is 2, including the trivial subfields.
  • One participant introduces a group theory perspective, stating that every field can be viewed as a group under addition, and that subfields correspond to subgroups, with the order of a subgroup dividing the order of the group.
  • A later reply expresses appreciation for the group theory insight, indicating a shift in understanding.

Areas of Agreement / Disagreement

Participants generally agree that F_p has no proper subfields, but there is some ambiguity regarding the inclusion of trivial subfields in the count. The discussion does not reach a consensus on the total number of subfields.

Contextual Notes

There are unresolved assumptions regarding the definitions of subfields and trivial subfields, as well as the implications of group theory on field structure.

Diffy
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Consider the prime field F_p p a prime.
How can I count the number of subfields there are?

Is this a known result of algebra?
 
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This is actually very easy. Try to convince yourself that F_p can't have any proper subfields.

In some sense F_p is the 'smallest' field of characteristic p.
 
This was my gut, I could not conceive how you could have a subfield. So the answer is 2, (because I still want to count trivial subfields).
 
The "known result" is actually a result from group theory: Every field is a group considering only its addition operation and every subfield is a subgroup of that group. The order of a subgroup must divide the order of the group.
 
Thanks I wasn't thinking about it like that. I appreciate the insight.
 

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