Timeline for Checking a monad is idempotent
Current License: CC BY-SA 3.0
6 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Mar 31, 2017 at 7:07 | comment | added | HeinrichD | It would help if you add the details of the specific situation where this question arises from. | |
| Mar 29, 2017 at 19:08 | comment | added | Todd Trimble | Nope! You were totally fine. :-) | |
| Mar 29, 2017 at 18:22 | comment | added | Dylan Wilson | (Tone doesn't parse well on the internet. Sorry if that came across brusque!) | |
| Mar 29, 2017 at 18:06 | comment | added | Dylan Wilson | Thank you- I was aware of both of these. The reason I mentioned the "really want to know" piece was in case there was a criterion to check that involved knowing something about the category of algebras. Equivalent statements are not always equivalently easy to check :) | |
| Mar 29, 2017 at 18:03 | comment | added | Todd Trimble | Two very quick reactions; I haven't thought about your question properly yet. (1) If $T$ preserves finite coproducts and filtered colimits, then it preserves infinite coproducts (perhaps you meant infinite coproducts when you said direct sums?). (2) A monad $T$ is idempotent iff the forgetful functor from the category of algebras is fully faithful, so your "really want to know" is already equivalent to the original question. | |
| Mar 29, 2017 at 17:52 | history | asked | Dylan Wilson | CC BY-SA 3.0 |