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Two Spies and a Paradox

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Edited by Richard Walker, Wednesday, 20 Jan 2016, 01:31

Once upon a time there were two spies, code-named M and N, who worked for rival departments.

By coincidence on one particular day M and N were both assigned to 24-hour surveillance of the email messages sent by a dastardly counterspy X to one of her accomplices Y.

The messages were cunningly encrypted, so the content was unreadable, but it was hoped that monitoring the number of communication would indicate whether or not a crisis was looming and action would need to be taken.

A downward trend during the day would indicate there was no cause for alarm; conversely an upward trend would indicate danger.

M counted the messages sent in each 12-hour period and submitted a report with a graph showing a clear downward trend.

N counted the messages sent in each 8-hour period and submitted a report with a graph showing a clear upward trend.

Yet the equipment used by each spy was perfectly reliable, and they recorded the data accurately. How can this paradox be explained?

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