Def .
Integral Domain :
A commutative ring with unity and without zero divisors is
called an integral domain
Results :
If R is a ring then
for all a, b, c ÎR , we have
1. a+ b = b +c Þ
b = c
2. (-a)= - a
3. The zero element of R is unique.
4. The additive
inverse of any element in R is unique.
5.a.0=0.a=0
6. a(-b)= -(ab)
7. Multiplicative inverse of a non-zero element, if exists,
is unique.
Key points:
1.
A commutative ring R with unity is an integral
domain iff cancellation laws holds in R.
2.
A
division ring is always without zero divisors.
3.
A field
is always without zero divisors.
4.
A field
is always an integral domain.
5.
A ring
with zero divisors cannot be an integral domain and field.
6.
Wedderburn’s theorem :
(i)
Every finite commutative ring without zero
divisors is a field.
(ii)
Every finite integral domain is a field. But an
infinite integral domain may or may not be a field.
Boolean Ring :
A ring (R,+,.) in which every element is
an idempotent is called a Boolean ring.
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