Got Homework?
Connect with other students for help. It's a free community.
Here's the question you clicked on:
 0 viewing

This Question is Open

KingGeorgeBest ResponseYou've already chosen the best response.0
Have you learned much about set partitions?
 one year ago

satellite73Best ResponseYou've already chosen the best response.0
i think this is not easy it is identical to asking how many partitions there are. maybe i am mistaken, but i don't think this has an obvious answer
 one year ago

satellite73Best ResponseYou've already chosen the best response.0
a quick google search finds these are bell numbers https://oeis.org/A000110
 one year ago

satellite73Best ResponseYou've already chosen the best response.0
or scroll down to "counting possible partitions" here http://en.wikipedia.org/wiki/Equivalence_relation
 one year ago

KingGeorgeBest ResponseYou've already chosen the best response.0
It's actually rather straightforward to figure this out. You can make a bijection between the set of set partitions and the set of equivalence relations on a set of n elements by equating partitions to equivalence classes.
 one year ago

KingGeorgeBest ResponseYou've already chosen the best response.0
To prove this is actually a bijection, just notice that it has an easy inverse (either way you go, just relabel set partitions as equivalence classes and vice versa). Thus, since it has an inverse, it must be bijective.
 one year ago

satellite73Best ResponseYou've already chosen the best response.0
ok, but how do you count them?
 one year ago

KingGeorgeBest ResponseYou've already chosen the best response.0
Well, that's a different story.
 one year ago
See more questions >>>
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.