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Topology

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Topologies on Finite Sets III

TOPO-DEQNW7

Which of the following is not a topology on the set $X=\{a,b,c\}$?

Select ALL that apply.

A

$\tau_1 = \mathcal{P}(X)$

B

$\tau_2 = \{\{a\}, \{b\}, \{c\}, \{a,b\}, \{a,c\}, \{a,c\}, X\}$

C

$\tau_3 = \{\emptyset, \{a\}, \{a,b,c\}\}$

D

$\tau_4 = \{\emptyset, \{a\}, \{b\}, \{a,b,c\}\}$

E

$\tau_5 = \{\emptyset, \{a,b,c\}\}$