Definition 4.1.2 (Ring).label Let $X$ be a set and $\cali{A}\suf 2^{X}$, then $\cali{A}$ is a ring if:
- (A1)
$\emp,X\in\cali{A}$
- (A2’)
$\fall E,F\in\cali{A}$ with $E\suf F,F\del E\in\cali{A}$
- (A3)
$\fall E,F\in\cali{A},E\cup F\in\cali{A}$
Definition 4.1.2 (Ring).label Let $X$ be a set and $\cali{A}\suf 2^{X}$, then $\cali{A}$ is a ring if:
$\emp,X\in\cali{A}$
$\fall E,F\in\cali{A}$ with $E\suf F,F\del E\in\cali{A}$
$\fall E,F\in\cali{A},E\cup F\in\cali{A}$
Post a Comment