Some math institutes offer programs in which a small number of researchers are enabled to meet at the institute for a week or more. A list seemed as if it could be useful.
As far as I know, the "Research in Pairs" program appeared first and still exists in the Mathematisches Forschungsinstitut Oberwolfach. See http://www.mfo.de/
As for the list of such possibilities, one can look through the list of all institutes of this kind: http://www.math.psu.edu/MathLists/institutes.php
BIRS in Banff, Alberta, Canada, offers "research in teams" (2-4 people, 1-2 weeks) and "focussed research groups" (up to eight researchers, 1-2 weeks).
The Hausdorff Institute in Bonn (http://www.hausdorff-research-institute.uni-bonn.de/index) offer research in small groups of size at least 3.
This is a little bit off the beaten path, and definitely not for all personalities, but the high school summer program Canada/USA Mathcamp has a Research in Pairs program (details here) for which we're happy to receive unsolicited applications. In brief: collaborators visit the program, teach 1 hr/day (on whatever they'd like) to very very bright high school students, and spend the rest of their time on their research program.
a. Institut Henri Poincaré (Paris)
'Research in Paris' (yes, Paris not pairs)
http://www.ihp.fr/en (under "Activities" one will find "Research in Paris")
b. CIRM (Marseille/Luminy)
'Recherche en binôme' / Research in pairs
http://www.cirm-math.com/ (under "Scientific" one will find "research in pairs")
The American Institute of Mathematics in San Jose has a nice program for collaborations:
As of today, an additional option exists at EPFL:
RIMS Kyoto says (in Japanese) they host at least two for 1-2 weeks collaboration http://www.kurims.kyoto-u.ac.jp/ja/research-01.html
There is also a Research in Pairs program at the ICMAT, in Madrid. From the institute page,
Research in pairs Programme aims at small groups of 2-4 researchers from different places working together on a specific project for a short period of time.
The Mittag-Leffler institute near Stockholm has another RIP (this time it stands for "Research in peace") programme.
There’s more information on the linked page, but the gist of it is this:
- 2-4 researchers wishing to organise a short, intensive period of research in Edinburgh
- at least one researcher must be based in the UK
- not all researchers should be from the same university, with a maximum of two researchers from any one university
There are three deadlines for submitting a Research-in-Groups proposal each year: 30 April, 30 August and 30 December.
The CIRM in Trento (Italy) has a Research in pairs program (for 2-3 people, 1-6 weeks):
This program is fairly new, but I can say from experience that it's a beautiful facility and great working environment.
Collaborate@ICERM offers teams of 3-6 researchers the opportunity to spend five days at the institute during the summer (May-August) or in the month of January. The team research project should have a computational or experimental component.
The Erwin Schrodinger Institute in Vienna has a research in teams program: https://www.esi.ac.at/activities/research-in-teams-short
Unlike some other programs, this supports visits of 1 - 4 months.