1 U means usual topology on R 2 H means halfopen interval to

1. U= means usual topology on R

2. H =means half-open interval topology on R

3. C =means open half-line topology on R

4. D= means discrete topology on any set X

5. I= means indiscrete topology or the trivial topology on any set X

6. F=finite complement topology on any set X

7. CC=countable complement topology

usual topology:

a.open

b.not open

c.not open

d.open

e.open

f.open

g.open

h.open

Half-open interval topology