20190718, 17:24  #23 
"Robert Gerbicz"
Oct 2005
Hungary
10100111001_{2} Posts 
If somebody wants to recheck the result it would be enough to upload say every millionth bit of pi, to enable a "fast" check using the https://en.wikipedia.org/wiki/Bailey...louffe_formula . I would do this. Anything else is a total waste of bandwidth.

20190718, 17:40  #24  
Jan 2015
251 Posts 
Quote:
That idea is appreciated....if anyone wants a physical copy they can come to Salt Lake and get it 

20190718, 17:41  #25  
Sep 2016
7·47 Posts 
Quote:
Code:
hash10 = floor(pi * 10^(# of decimal digits)) % M61 hash16 = floor(pi * 16^(# of hexadecimal digits)) % M61 So it provides a way to verify the integrity of the digits at any point in the future. These hashes can also be verified in parallel. So if the data is distributed, you can compute the local hashes onsite then do a reduction at the end. 

20190719, 17:05  #26 
Jan 2015
251_{10} Posts 
Soo to put it in simpler terms... can the validation be done quick small and easy?

20190719, 18:27  #27  
Sep 2016
7×47 Posts 
Quote:
If you want to validate the digits of an already completed computation:
If you want to validate the digits of a newly finished computation, the only thing you need to do is run the BBP formula to verify that the last few hexadecimal digits are correct. Other forms of verification are needed to make it more rigorous, but these are all handled automatically by ycruncher (if you turn them on):
Last fiddled with by Mysticial on 20190719 at 18:38 

20190719, 19:25  #28  
"Robert Gerbicz"
Oct 2005
Hungary
7×191 Posts 
Quote:
start the file with the known bits of pi, then totally random fake sequence, and end with some correct bits calculated with BBP. ps. ofcourse your method is good if you want to validate your(!) own computation. Last fiddled with by R. Gerbicz on 20190719 at 19:28 

20190719, 21:16  #29 
Jan 2015
251 Posts 

20190719, 21:48  #30  
Sep 2016
7×47 Posts 
Quote:
First of all, there's no known way to verify *all* the digits of Pi from 1 to N in any base that's more efficient than recomputing them and comparing with the suspect digits. But the next best thing you can do is a "proofofcomputation". The suspect source makes all the (binary) digits available with little latency. That is anybody can ask the suspect for binary digits at an arbitrary offset and the suspect will be able to produce them instantly. As the verifier, you can pick random offsets, use BBP to compute the digits, and then test the suspect. The security here relies on:
So if the suspect can instantly produce the correct digits at arbitrary offsets, the only reasonable explanations are:
And if the latter, the suspect has accomplished something much more worthy than having done the computation. Last fiddled with by Mysticial on 20190719 at 21:54 

20191011, 14:45  #31  
"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest
5·7·109 Posts 
Quote:


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