I need to prove the following whether it is true or not
Let A = [ a, {b, c, d}, {e}, f, {g, h}, {i, j}, k ]
1. {b, c, d} ∈ A
2. {{i, j}} ⊆ A
3. ∅ ∈ A
4. {i, j, k} ∈ A
5. {a} ⊆ A
but I am not sure what does a set with square brackets and curly braces inside it mean. Please help me, thank you!
Let A = [ a, {b, c, d}, {e}, f, {g, h}, {i, j}, k ]
1. {b, c, d} ∈ A
2. {{i, j}} ⊆ A
3. ∅ ∈ A
4. {i, j, k} ∈ A
5. {a} ⊆ A
but I am not sure what does a set with square brackets and curly braces inside it mean. Please help me, thank you!