18.6.1. Let R be a non-trivial commutative ring with identity. Show that the following are equivalent: (a) R is local. (b) The set of all non-units of R forms an ideal of R. (c) The sum of any two non-units in R is a non-unit. (d) If x ЄR, then x or 1 - x is a unit.

Elements Of Modern Algebra
8th Edition
ISBN:9781285463230
Author:Gilbert, Linda, Jimmie
Publisher:Gilbert, Linda, Jimmie
Chapter6: More On Rings
Section6.1: Ideals And Quotient Rings
Problem 24E: 24. If is a commutative ring and is a fixed element of prove that the setis an ideal of . (The set...
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18.6.1. Let R be a non-trivial commutative ring with identity. Show that the
following are equivalent:
(a) R is local.
(b) The set of all non-units of R forms an ideal of R.
(c) The sum of any two non-units in R is a non-unit.
(d) If x ЄR, then x or 1 - x is a unit.
Transcribed Image Text:18.6.1. Let R be a non-trivial commutative ring with identity. Show that the following are equivalent: (a) R is local. (b) The set of all non-units of R forms an ideal of R. (c) The sum of any two non-units in R is a non-unit. (d) If x ЄR, then x or 1 - x is a unit.
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