Definition of Z^*_p: Introduction to Ring Theory

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SUMMARY

The notation Z^{*}_{p} refers to the set of integers modulo p that have a multiplicative inverse, specifically defined as Z_{p} - {0}. In ring theory, Z_{p} represents integers under addition modulo p, while Z^{*}_{p} consists of integers from 1 to p-1 under multiplication modulo p. This distinction is crucial as Z^{*}_{p} forms a group with multiplication as the operation, contrasting with the additive structure of Z_{p}.

PREREQUISITES
  • Understanding of ring theory concepts
  • Familiarity with modular arithmetic
  • Knowledge of group theory fundamentals
  • Basic definitions of fields and multiplicative inverses
NEXT STEPS
  • Study the properties of multiplicative groups in modular arithmetic
  • Explore the structure of finite fields and their applications
  • Learn about the Chinese Remainder Theorem and its implications in ring theory
  • Investigate the relationship between Z_{p} and Z^{*}_{p} in greater detail
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Students of abstract algebra, mathematicians focusing on ring theory, and anyone interested in the properties of modular arithmetic and group structures.

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Homework Statement


I'm studying introductory ring theory and have encountered the notation Z^{*}_{p} with no definition attached. If anyone could provide the definition for this, that would be great.

Homework Equations


Don't think there are any...

The Attempt at a Solution


The only way I've ever encountered * above anything was in the dual space, and I'm pretty convinced it has nothing to do with it.
 
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Never mind, I got it, it's Z_{p}-0.
 
For a ring R, the notation R* is usually used to denote the set of elements that have a multiplicative inverse. (This set is actually a group, with the operation being multiplication)

The equation R* = R - {0} is valid if and only if R is a field.
 
OB1 said:
Never mind, I got it, it's Z_{p}-0.
No, it's not. Zp specifically means the integers with addition modulo p.

Z*p is the integers, other than 0, with multiplication modulo p.
You can take the members of Zp to be 0, 1, 2,..., p-1 and the members of Z*p to be 1, 2, ..., p-1 but the operations are different.
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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