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        riddles >> hard >> MESSAGE RECONSTRUCTION
        
(Message started by: kapiwu on Dec 9^th, 2007, 9:54pm)

Title: MESSAGE RECONSTRUCTION
Post by kapiwu on Dec 9^th, 2007, 9:54pm

alice sends different partial messages to a bunch of different receivers. by partial, we mean that one message by itself doesn't convey any meaningful information. let us denote the set of receivers as R. the messages are designed such that if any n receivers get together, they can somehow pool their partial messages together to get a meaningful message -- alice's intended message. however, if any n-1 or less receivers get together, they can't reconstruct anything meaningful whatsoever. n < |R|. what kind of messages are being sent by alice, and what mathematical function do the receivers apply on their pooled partial data to determine the intended message?
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I had tried to search this in the forum and net but not found. Can anybody tell the solution for the above?

Title: Re: MESSAGE RECONSTRUCTION
Post by towr on Dec 10^th, 2007, 1:29am

It is on the forum in a different form, where they use locks and keys such that |R| people can together unlock the box/treasure/message/whatever, but fewer can't.
I don't recall the solution at the moment though.

Title: Re: MESSAGE RECONSTRUCTION
Post by towr on Dec 10^th, 2007, 1:51am

Here's the thread: "A Strongbox Puzzle" (http://www.ocf.berkeley.edu/~wwu/cgi-bin/yabb/YaBB.cgi?board=riddles_easy;action=display;num=1163664413;start=5#5)