3. Which of the following is a basis for a topology on X = {1,2,3,4} (a) {{1}, {1,2}, {1,3}} (b) {{1, 2}, {2,3,4}} (e) {

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3 Which Of The Following Is A Basis For A Topology On X 1 2 3 4 A 1 1 2 1 3 B 1 2 2 3 4 E 1 (23.35 KiB) Viewed 17 times

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3. Which of the following is a basis for a topology on X = {1,2,3,4} (a) {{1}, {1,2}, {1,3}} (b) {{1, 2}, {2,3,4}} (e) {{1,2}, {1, 2, 3}, {1, 2,4}} (d) {{1,2}, {2,3,4}, {1,3,4}} 4. Each of the following set is open with respect to the cofinite topology on R except for one. Which one is it? (a) {1 ER24 +3.0 – 2+0} (b) R\{2} (e) {x ER | x is irrational} (d) {1 ER2= -1}