Last week we had a pPTQ. During a match, a player called a judge, as we approached, AP told us that he asked his opponent how many cards he held in his hands, then NAP said “enough” and showed his hand to AP, he had 3 cards on it. Since both confirmed the story, I issued a Warning to NAP for TE-CPV. Later, another judge pointed out something that makes me doubt my decision, he showed me that the number of cards in the hands of any player is a derived information, so players aren't obligated to give this information to his opponents, but if they chooses to, they must give the right one. Then I started to think that, in this case, NAP didn't give the wrong information, he just chose to leave AP discover it by showing his hand. It would be different if NAP had said “4”, in this case there is no doubt it would be a TE-CPV, or UC-C if he was doing it on purpose.

MTR says:

Derived information is information to which all players are entitled access, but opponents are not obliged to assist in determining and may require some skill or calculation to determine. Derived information includes:

• The number of any type of objects present in any game zone.

Also, it says:

• Players may not represent derived or free information incorrectly.

It don't says anything about don't giving this kind information.

So what would be correct?

Edited Gregory Farias (June 23, 2015 02:13:57 AM)

The philosophy behind derived information is (according to me) rather clear cut.

• You are not obliged to answer questions from your opponent about derived information.
  
• If you answer questions about derived information you have to answer them truly. (i.e. not misrepresenting)
  

Edited Jonas Drieghe (June 23, 2015 02:20:37 AM)

I wouldn't have given the warning in the situation described. NAP is not required to tell AP the amount of cards in his hand; his responsibilities are (1) not to tell an amount that is false (MTR 4.1) and (2) to permit AP to count the cards (CR402.3).

Edited to change square to round brackets, keep forgetting that this forum doesn't like square brackets

Edited Thomas Ralph (June 24, 2015 05:29:10 AM)

Originally posted by Thomas Ralph:

I wouldn't have given the warning in the situation described. NAP is not required to tell AP the amount of cards in his hand; his responsibilities are (1) not to tell an amount that is false and (2) to permit AP to count the cards .

I agree. A Warning for this is way too harsh.

Of course, would NAP answer “Didn't you learn to count at school?” or similar, I would think about USC-Minor.
But in the described case, nothing happened.

Originally posted by Francesco Scialpi:

I agree. A Warning for this is way too harsh.

Harshness is not a determining factor in giving out a penalty; the IPG determines what penalties can (and should) be given. Because there is no infraction, there is no need to give a penalty, so any penalty here would be “too harsh”.

The fact that the number of cards in hand is derived information always sounded strange to me. What is the opponent supposed to derive it from? The number of cards in the deck is not public, so counting the library will not be enough.

It's derived by counting the cards in the hand, usually by having the opponent lay down the hand and spread it out in a way that it can be easily counted. This is why most players will simply answer the question of how many cards, because there is no real advantage to testing the opponent's ability to count to something as high as 7 in most cases…

It is “derived” because it is calculated. In this case by simple counting, but that is in itself a skill. There's an opportunity for error.

Don't believe me? Try counting or doing addition/subtraction after years of calculus. :P