When trying to find all the partitions of a set; there should always be at least one partition (the original set itself)?
I'm trying to confirm this by listing all the partitions of these two sets...
- First set: A = {a, b, c}
P(A) = {{}, {a}, {b}, {c}, {a, b}, {a, c}, {b, c}, {a, b, c}}
Partition: {{a}, {b}, {c}}
Partition: {{a}, {b, c}}
Partition: {{b}, {a, c}}
Partition: {{c}, {a, b}}
Partition: {{a, b, c}}
- Second set: B = {1, 2}
P(B) = {{}, {1}, {2}, {1, 2}}
Partition: {{1}, {2}}
Partition: {{1, 2}}
Yes, this looks correct.
One quick way to check if you've listed all of them is to check if the number of partitions of your $n$-element set is equal to the $n^{th}$ Bell Number.