- #1

- 5,049

- 7

The below relations are given AUFTRAG($A_1, A_2, A_3$) and KUNDE($B_1, B_2, B_3$) with $A_1$ = AUFTRNR, $A_2$ = DATUM, $A_3$ = KUNDNR, $B_1$ = KUNDNR, $B_2$ = NAME and $B_3$ = ORT.

Determine the below sets or justify why it is not possible to determine them.

1. It holds that $\text{AUFTRAG}\cup \text{KUNDE} = (A_1, A_2, A_3)\cup (B_1, B_2, B_3)$. Since $A_3$ and $B_1$ are not entirely distinct we can use the first property, can't we? Or isn't this correct because these sets are notat the same position at the respective tupel? :unsure:

2. It holds that $\text{AUFTRAG}\cap \text{KUNDE} = (A_1, A_2, A_3)\cap (B_1, B_2, B_3)$. Here we can use the third property and so it holds that $\left (A_1\cap B_1 , A_2\cap B_2 , A_3\cap B_3\right )$, right? :unsure:

3. It holds that $\text{AUFTRAG}\times \text{KUNDE} = (A_1, A_2, A_3, B_1, B_2, B_3)$, or not? So we take all posible combinations for that set, don't we? :unsure:

4. We take the result of 3 and we replace $B_3$ everywhere by "Gießen", right? :unsure: