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Ponder This

December 2016

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Ponder This Challenge:

The European Union's General Data Protection Regulation (GDPR) is bolstering privacy protection in general and for biometric features in particular.
We would like to hold a competition, but to make it fair we'd like to have all the participants be of similar strength.
Let's assume (for the sake of the challenge) that all the men can apply exactly the same force in a rope-pulling contest, and all the women can apply a different force, but again, same for all.
We want to make sure that all the participants have the same gender.
The simple way to do that (asking for gender in the application form) is not an option (since it might be regarded as a biometric feature), so instead we use a rope-pulling contest.
We have time for four such contests, where we can chose any two equal-sized disjoint subsets of participants and let them compete. If any of these four contests ends not in a tie (i.e., one group wins) then, of course, we've proved that our group is not mono-gender.
We need to find four contests that can prove that all the N participants have the same gender.
For example, here is such a solution for a group of N=16 people:
A ; B
A B ; C D
A B C D ; E F G H
A B C D E F G H ; I J K L M N O P
The challenge, this month, is to find a solution for N at least 27. Bonus '*' for bigger Ns. Use "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789" to mark the participants.

Want to learn more about compliance with the new European data privacy guidelines? Visit the IBM Research Meeting GDPR page.

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Challenge: 29/11/2016 @ 12:00 PM EST
Solution: 02/01/2017 @ 12:00 PM EST
List Updated: 25/12/2016 @ 12:00 PM EST

People who answered correctly:

***Bert Dobbelaere (03/12/2016 11:08 PM IDT)
***Arthur Vause (06/12/2016 04:46 PM IDT)
***Luke Pebody (07/12/2016 01:20 AM IDT)
***Tamir Ganor & Shouky Dan (08/12/2016 09:14 AM IDT)
***Jesse Rearick (09/12/2016 05:37 AM IDT)
***Aviv Nisgav (12/12/2016 02:54 PM IDT)
***Jamie Jorgensen (12/12/2016 05:54 PM IDT)
***Uoti Urpala (13/12/2016 05:21 AM IDT)
***Liubing Yu (13/12/2016 10:01 AM IDT)
***Mtv Europe (13/12/2016 04:15 PM IDT)
***Radu-Alexandru Todor (14/12/2016 01:46 AM IDT)
***Jim Roche (14/12/2016 06:01 AM IDT)
***Shirish Chinchalkar (16/12/2016 02:32 AM IDT)
***YanWu-He (16/12/2016 01:32 PM IDT)
***Tomáš Jurík (22/12/2016 02:27 PM IDT)
***Todd Will (22/12/2016 09:56 PM IDT)
***Pål Hermunn Johansen (23/12/2016 08:54 PM IDT)
*Tyler Mullen (25/12/2016 02:24 PM IDT)
*Aradesh (27/12/2016 02:39 PM IDT)
***Zusheng Ji (27/12/2016 04:05 PM IDT)
***David Greer (28/12/2016 05:19 PM IDT)
***Siddharth Joshi (28/12/2016 06:30 PM IDT)
***Vladimir Dorofeev (29/12/2016 06:47 PM IDT)
***Kang Jin Cho (30/12/2016 11:21 AM IDT)
***Hao Wu (30/12/2016 11:35 PM IDT)
***George W Barnett (31/12/2016 12:15 AM IDT)