Two Oddities today

RikerKirk

New member
Mar 8, 2005
197
0
0
Two Oddities today

Running Meph and ran across 2 very strange occurences


1. Two completely unrelated items, a Bveritt shield and a Noz Amulet, had exactly the same fingerprint.

2. Got a Arach Mesh to drop, but on the same drop, TWO green breastplates dropped, I picked them both up and they had different fingerprints, but I thought it was impossible for more than one of the same item to drop in the same game, although I could be wrong.
 
Re: Two Oddities today

on 2: Nar, I see it all the time.

The same fingerprint. The odds are infintesimal that it would happen to any two items, especially in the same drop.

Edit: assuming that the hex number can be anywhere from 00000000 through to ffffffff, then thats 16^8 possible fingerprints. 4,294,967,296 possibilities. So the chances of that happening for any two items is one in 4.3 billion. Which means that it pretty much didn't happen...
 
Re: Two Oddities today

I dont believe it was on the same drop, just within an hour or so, Ive never seen that happen ever so when Flavie came up with a dupe warning I was quite suprised when they were different items
 
Re: Two Oddities today

on 2: Nar, I see it all the time.

The same fingerprint. The odds are infintesimal that it would happen to any two items, especially in the same drop.

Edit: assuming that the hex number can be anywhere from 00000000 through to ffffffff, then thats 16^8 possible fingerprints. 4,294,967,296 possibilities. So the chances of that happening for any two items is one in 4.3 billion. Which means that it pretty much didn't happen...
You're correct about the odds of a single randomly generated item having the same fingerprint as one specific other item, but the odds are different for simply finding a collision of fingerprints among a large set of items (this is an example of the Birthday Problem).

If a fingerprint is 32 bits, then a stash of ~77000 fingerprinted items has a 50% chance of a fingerprint collision.



 
Re: Two Oddities today

thanks for doing the math on that Oscuro.

I have been playing off and on for over 5 years at least, and its the first time I have ever seen it. The freaky part was that both items dropped in the same sitting instead of one of them matching an existing item in my stash.

Just in case anyone was curious

Code:
Bverrit Keep
Tower Shield
Defense: 78
Chance to Block:  54%
Smite Damage: 1 to 5
Durability: 40 of 158
Required Strength: 75
Required Level: 19
Item Version: 1.10+ Expansion
Item Level: 87
Fingerprint: 0x8aeadd1a
+5 to Strength
+88% Enhanced Defense
+10% Increased Chance of Blocking
+30 Defense
Magic Damage Reduced by 5
Fire Resist +75%
+98 Maximum Durability

Nokozan Relic
Amulet
Required Level: 10
Item Version: 1.10+ Expansion
Item Level: 87
Fingerprint: 0x8aeadd1a
Fire Resist +50%
+10% to Maximum Fire Resist
Adds 3-6 fire damage
+3 to Light Radius
20% Faster Hit Recovery
 
Re: Two Oddities today

Ah I misread it a bit. Thought it was double fingerprint on the same drop. I know that my odds were off even for that, but it was similar enough :p I guess it was bound to happen eventually, even with such a large range of possibilities.

out of interest, how large is the stash?
 
Re: Two Oddities today

So for any two out of 4000 items having the same fingerprint (4.3 billion possibilities as stated above) the calculation is:

... way too large for my calculator. It requires some large factorials. Help?
 
Re: Two Oddities today

The "Only one of each item per session" rule only applies to Uniques, as far as I can tell.
 
Re: Two Oddities today

The "Only one of each item per session" rule only applies to Uniques...

which would be why they're called "uniques". :crazyeyes:



 
Re: Two Oddities today

And that's why green breastplates are classified as sets. Cause you always say "s(h)et!, another one?"
 
Re: Two Oddities today

If a fingerprint is 32 bits, then a stash of ~77000 fingerprinted items has a 50% chance of a fingerprint collision.
I very much doubt it. A 32-bit fingerprint has ~4.3 billion different possibilities. 77000 is not even near a promille of that.

My guess is that you are running with the -seed command, or you should buy a lottery ticket.



 
Re: Two Oddities today

If a fingerprint is 32 bits, then a stash of ~77000 fingerprinted items has a 50% chance of a fingerprint collision.

Just out of curiousity, how did you calculate this?

This is what I tried. If there are 2^32 (= approx. 4.3E9) possible fingerprints, the chance of N items having no collisions is:

P = 1(1-p)(1-2p)(1-3p)...(1-(N-1)p)

with p = 1/(2^32)

I suck too much at math to simplify this properly, but since p is small, disregarding all terms with order 2 and higher should not cause a huge error, therefore:

P = 1-p-2p-3p...-(N-1)p = 1-0.5(N^2-N)p

Solving for P = 50% gives N ~ 65,000. This is close to your 77,000. The difference could be caused by my simplification, because all 2nd order terms are positive, so I am overestimating P, and therefore underestimating N.

However, after my miscalculation earlier this week I'm not so confident about my mathematical skills anymore. :p



 
Re: Two Oddities today

If a fingerprint is 32 bits, then a stash of ~77000 fingerprinted items has a 50% chance of a fingerprint collision.

So for any two out of 4000 items having the same fingerprint (4.3 billion possibilities as stated above) the calculation is:

... way too large for my calculator. It requires some large factorials. Help?

Just out of curiousity, how did you calculate this?

If only you knew the power of the dark side: arbitrary precision.

Guess who watched Episode V last night.

Code:
birthday(N) =
{

    local(p,pr);

    p = 1/4300000000;
    pr = 1;

    for( i=1 , N-1 ,
        pr = pr*(1-i*p);
        );

    return(pr*1.0);

}

Yes, yes, it could have been much more efficient using factorials....

If there are 77000 items in the stash, then the chance of no collision is: 0.5018701960892096205363006948

If there are 4000 items in the stash, then the chance of no collision is: 0.9981417281524217685192899572


 
Re: Two Oddities today

which would be why they're called "uniques". :crazyeyes:

Though two of the same unique item can (or at least could in previous patches, I haven't had it happen in 1.12) drop at the same time. I have a few screenshots of Meph dropping pairs of uniques.


 
Re: Two Oddities today

Oh hey whommy, glad to see you're still posting. :)

Though two of the same unique item can (or at least could in previous patches, I haven't had it happen in 1.12) drop at the same time.

I thought so too, but Hrus's tests suggest it's impossible, at least in 1.11. Must be in 1.09 or 1.10 or something. I was so sure I had it happen to me too.



 
Re: Two Oddities today

Yes, yes, it could have been much more efficient using factorials....

More efficient would be using the formulas on the other wiki page ;) :

P(2^32, 77000) = exp(-(77000^2-77000)/2/2^32) = 0.5015
P(2^32, 4000) = exp(-(4000^2-4000)/2/2^32) = 0.9981

essojay said:
whommy said:
Though two of the same unique item can (or at least could in previous patches, I haven't had it happen in 1.12) drop at the same time.
I thought so too, but Hrus's tests suggest it's impossible, at least in 1.11. Must be in 1.09 or 1.10 or something. I was so sure I had it happen to me too.

How about rainbow facets? Can you find 2 of them in 1 session, as long as they're of a different type? Would that be similar to the Lightsabre + Azurewrath drop mentioned in Hrus' thread?



 
Re: Two Oddities today

Though two of the same unique item can (or at least could in previous patches, I haven't had it happen in 1.12) drop at the same time. I have a few screenshots of Meph dropping pairs of uniques.

If they could before, they can't anymore. I've had a unique and a triple-durability rare of the same item type from the same drop, which means the unique rolled twice, but couldn't drop twice.



 
Diablo 4 Interactive Map
PurePremium
Estimated market value
Low
High