Fabien's open letter to the community

[bob]

Bob, a big difference between 1995 and now is that now you can encrypt, zip and email the source to yourself and it will take you 3 minutes. It is that simple.

I read long time ago when Strelka came out someone asked Vasik whether it might be possible that his code got stolen, he said no, because he keeps it a dedicated computer with no internet connection.

A person who takes such precautions would surely take a minute or two to take care he has a backup copy.

How would that help? My email is on the same machine as the master Crafty source...

[Gian-Carlo Pascutto]

Is it also plagiarism?

You didn't post complete code. The real code is identical except for the or-ing in of the X-Ray attacker, right? Something that you can find in crafty, Stockfish, or any other open source bitboard program.

But, what to say of the comparison against the (arbitrary) constant -60? Where does it come from and why do both programs have exactly the same?

Can you enlighten me?

[Adam Hair]

Wow, your graphs are almost identical to mine, therefore we can cross-check our results. I will stick to "Average Linkage between Groups" and "Pearson correlation (bivariate correlations) measure", as these give me the more stable results over all the range, from main branches to individual engines.
I added Crafty 20.14 and some claimed to be related to it engines, and, as expected, they seem indeed related . Now the Crafty family is represented as well. My Crafty test was a pain, with a very slow WB2UCI interface, it took me 5 hours to test Crafty at 100 ms.



A and B are two groups of very unrelated engines. Group A might be related in some degree to Fruit. Group B seems not related at all to Fruit (if the Fruit hypothesis stands). Crafty, Fruit 2.1, and Rybka 3 families are named.

Kai

With some WB engines, the test is much quicker.

I need to test Kaissa 1.8 and some more Craftys.

[Gerd Isenberg]

Students are quite good at this kind of obfuscation. One can do the above to improve speed (one popcnt vs N BSF instructions in a loop) or to make the code appear to be different (both do the same thing, but look significantly different, particularly if you change the variable names as well...

You are very strong teacher. I would not want to be your student.

Another example. In the function SEE of Ivanhoe, we can find the following:

Code: Select all

  do
    {
      cbf &= ~bit;
      mask = BitboardOppP & bit;
      if (mask)
	{
	  bit ^= (~(mask - 1)) & mask;
	  PieceValue = ValueP;
	}
      else
...

Obviously, this is a mistake. After the capture by a pawn on the open diagonal can be an bishop or a queen. In Houdini this bug is corrected:

Code: Select all

  while (bit & OppOccupied) {
    if (mask = BitboardOppP & bit)
      {
        capture_value += 100;
        if &#40;capture_value < -60&#41; return 0;
        from = first_one&#40;mask&#41;;
        occ &= ClearBit&#91;from&#93;;
        bit &= ClearBit&#91;from&#93;;
        bit |= BMagicAttacks&#91;BishopIndex&#40;to, occ&#41;&#93; & diag & occ;
      &#125;
    else
...

Is it also plagiarism?

I would not call not considering X-rays in SEE a bug but a design descision.

SEE swap algorithm is more in the public domain with some freedom to implement things differently, which had happened here. Even one may formulate the two's complement aka -mask per definition as ~(mask - 1) or ~mask + 1. No idea on the -60 though.

I also see no plagiarism in formulating a dot-product for mobility by a bitboard serialization loop, multiplication with popcounts, or a SSE2 dot product. If weight constants are identical this is more questionable, not as lonesome feature but in conjunction with multiple other symptoms of similarity.

[Uri Blass]

Bob, a big difference between 1995 and now is that now you can encrypt, zip and email the source to yourself and it will take you 3 minutes. It is that simple.

I read long time ago when Strelka came out someone asked Vasik whether it might be possible that his code got stolen, he said no, because he keeps it a dedicated computer with no internet connection.

A person who takes such precautions would surely take a minute or two to take care he has a backup copy.

How would that help? My email is on the same machine as the master Crafty source...

I do not know about your email but I can check emails in every computer and I only need my username and my passward.

In other words the content of my emails are saved in a different place than my computer.

I use gmail.

[playjunior]

Bob, a big difference between 1995 and now is that now you can encrypt, zip and email the source to yourself and it will take you 3 minutes. It is that simple.

I read long time ago when Strelka came out someone asked Vasik whether it might be possible that his code got stolen, he said no, because he keeps it a dedicated computer with no internet connection.

A person who takes such precautions would surely take a minute or two to take care he has a backup copy.

How would that help? My email is on the same machine as the master Crafty source...

Send it to a friend or a family member.

[bob]

Bob, a big difference between 1995 and now is that now you can encrypt, zip and email the source to yourself and it will take you 3 minutes. It is that simple.

I read long time ago when Strelka came out someone asked Vasik whether it might be possible that his code got stolen, he said no, because he keeps it a dedicated computer with no internet connection.

A person who takes such precautions would surely take a minute or two to take care he has a backup copy.

How would that help? My email is on the same machine as the master Crafty source...

I do not know about your email but I can check emails in every computer and I only need my username and my passward.

In other words the content of my emails are saved in a different place than my computer.

I use gmail.

I don't use free email machines. Non-secure and I have too many discussions about student grades and such. My email is on my office box for the same security reasons. The US FERPA (Family Educational Right to Privacy Act) is pretty onerous and requires reasonable protection for student discussions. gmail, yahoo, etc do not provide that.

[bob]

Bob, a big difference between 1995 and now is that now you can encrypt, zip and email the source to yourself and it will take you 3 minutes. It is that simple.

I read long time ago when Strelka came out someone asked Vasik whether it might be possible that his code got stolen, he said no, because he keeps it a dedicated computer with no internet connection.

A person who takes such precautions would surely take a minute or two to take care he has a backup copy.

How would that help? My email is on the same machine as the master Crafty source...

Send it to a friend or a family member.

Which would mean "quantity over quality?" I have my sources backed up on three different machines, plus the occasional DVD dump in my office for a semi-permanent backup, multiple copies over time... I don't know who backs up their email. Most don't in fact, and leave it on the remote server which will probably dump it after a while.

[Milos]

I don't use free email machines. Non-secure and I have too many discussions about student grades and such. My email is on my office box for the same security reasons. The US FERPA (Family Educational Right to Privacy Act) is pretty onerous and requires reasonable protection for student discussions. gmail, yahoo, etc do not provide that.

OMG. I hope you've heard of IMAP????

[Milos]

Send it to a friend or a family member.

Which would mean "quantity over quality?"

10 highly unreliable friends are much more reliable overall than 3 highly reliable storages...
Basic statistics. Say probability for each of your friends to lose your emails is 10% and probability that one of your reliable storage fails is 0.1%.
Overall it's 0.1^10 = 1e-10 vs. 0.001^3=1e-9 .