# New tag for "stochastic partial differential equations" (SPDEs)

Since there are separate tags for a) ODEs, and and for b) but only one tag for , I was wondering if it is worth creating a new tag called "stochastic partial differential equations".

This is to accommodate the topics found in SPDE books such as Da-Prato and Zabczyk's book "Stochastic equations in infinite dimensions".

• Equations with additive noise or multiplicative noise
• Martingale solutions
• Large time behavior of solutions
• Small noise asymptotic behavior

and many new emerging topics such as

• Regularity structures
• Paracontrolled calculus
• Rough paths (which already has it own tag ).
• Some context: (1) the tag info for stochastic-differential-equations includes: "Stochastic ordinary and partial differential equations" (2) at this date, the number of questions with given tag: ap.analysis-of-pdes: 3795; ca.classical-analysis-and-odes: 3141; differential-equations: 1460; stochastic-differential-equations: 472.
– YCor
Nov 7 at 20:49
• The topics mentioned by the OP are clearly covered by the current tag stochastic-differential-equations. Whether a split of the latter tag would be opportune and clearly defined would require more expertise on this topic and knowledge of the involved mathematical communities than I have.
– YCor
Nov 7 at 20:50
• I agree with both. Nov 7 at 20:54
• It seems like a chicken-egg problem too. My thought is that by adding the SPDEs-tag it encourages more activity there too. Nov 7 at 20:55
• thank you,I fixed it. Nov 7 at 21:48
• Adding the tag (discussion) might improve chances that more people might notice this post and respond - only such questions appear in the community bulletin. (Additionally, the question needs to have score $\ge3$ and be at most 14 days old.) Tangentially to the issue raise here, I will point out that many questions about SDEs a re posted without a top-level tag. (See also: Why are MO tags formatted as they are?) Nov 10 at 5:55
• thank you, I added the discussion tag. Nov 10 at 6:54
• I have cast an upvote - mainly to get it to score +3. As you can see, it is now shown in the community bulletin: chat.stackexchange.com/transcript/10243/2022/11/10 Let's hope that this helps to get more feedback from MO users. Since this is a proposal for a new tag, I guess it would be useful to mention what would be the name of the new tag. (Or what are possible alternatives, if they are several.) And what the tag-excerpt and the tag-info would look like. (And whether there will be changes to the existing ... Nov 10 at 7:30
• ... tag-info for stochastic-differential-equations. As already mentioned, the tag currently includes SPDEs - after the creation of the new tag, will they be excluded from the old tag?) Nov 10 at 7:31
• Another natural question is what are the plans to do next if the tag is created. At least part of the questions tagged (stochastic-differential-equations) will need retagging by the new tag. Will somebody volunteer to do the manual retagging of older questions (or at least the more important ones)? Will other issues be address when retagging, too? (E.g., the missing top-level tags.) Nov 10 at 7:31
• Have you attempted to estimate, among the 470 existing questions, the proportion that concern stochastic PDEs? If their number is significant (say $>100$), it would not be reasonable to remove the PDE aspect from the current tag.
– YCor
Nov 11 at 14:30
• Since there are already only 68 watchers for the SDE tag, not sure there is a real need for an SPDE tag right now. Nov 20 at 12:04