Game Theory Question - Traveler's Dilemma with $2 reward, but with no penalty

What would be a dominant strategy in the Traveler's dilemma, if there is a $2 reward for having a lower number, but no $2 penalty for having a higher number? Would the final Nash equilibrium be (0,0)?

6 Comments
 

I am no expert so please someone correct me if I'm wrong (and assuming you find out the right answer, let me know). Here's my take:

Let's assume that there's a cap at $100 that one can guess. In the original game (where there is +2 for lower number and -2 for higher number) we start out 100,100. Realizing 1 can get more money if he undercuts 2, he offers 99,100 making the payoffs 101,98. Realizing 2 increase his payoff if he undercuts 1, he offers 99,98 making the payoffs 97,100. This goes on and on until both players offer the minimum. What makes this happen is the constant incentive to undercut the other player, driving the reward down to the minimum.

BUT, let's take a look at the modified game with no -2. Both start at 100,100. Player 1 undercuts 99,100 making payoffs 101,100. Should 2 undercut 1? If he does, that makes it 99,98 with payoffs 99,100. That's the same payoff that he had before. If you keep going, you'll see this continue with the pattern of each player having -2 each payoff, yet the effect is staggered (meaning it will be 99,100...99,98...97,98...97,96...) This is why I'd say the nash equilibrium is 99,100 payoff 101,100, because 2 has no incentive to deviate because he'd get the exact same payoff (unless he gets utility from 1 having less money).

I hope this makes sense and please let me know if I made any errors/what the right answer is.

 

I should've added they make their moves simultaneous, and the other person (who didn't undercut) receives the undercut price.

So, player 1 undercuts player 2, so payoff is 101,99 because player 1 chooses 99, and 99100, so he gets +2, so player 1 has 101, while player 2 stuck with 99 (the low number chosen by player 1). Should 2 now undercut 1? Well, yes. He can improve by undercutting at 98 such that he gets 98 + 2 = 100 and player 1 gets 98, so we have 98,100.

I don't actually know what the answer but would that logic follow through to the point 0,0?

 
Best Response

I don't believe that the incentive structure that initiates the backwards-induction down to (0,0) has been altered by removing the penalty. The function that drives down each bid is still intact -- Player A's payout is optimized by bidding 1 below Player B. The inverse is true for Player B, and both are aware of each other's strategy. This is true at an opening gambit of 100, or all the way down to 1.

A Nash equilibrium is only satisfied if no marginal gain is available by a change in strategy. Since both players marginal gain is always improved by bidding X - 1, where X is the other player, then the recursive nature of this relationship inevitably drives it to (0,0). Both players are assumed to be mechanistic actors so there is no escape from it.

That's considered the paradox of rationality which some believe undermine the merit of game theory. Truly mechanistic game-theoretical reasoning can lead to absurd results that are sub-optimal to those achieved by pure intuition.

 

Enim quae consequatur facere ipsum expedita asperiores ut aperiam. Voluptatum velit repudiandae magni iure voluptatem. Maiores autem odit tenetur consequatur qui dolor laborum.

Career Advancement Opportunities

July 2026 Investment Banking

  • Evercore 01 99.4%
  • Moelis & Company 01 98.9%
  • JPMorgan 01 98.3%
  • Goldman Sachs 01 97.8%
  • Guggenheim Partners No 97.2%

Overall Employee Satisfaction

July 2026 Investment Banking

  • Moelis & Company No 99.4%
  • Evercore No 98.9%
  • Morgan Stanley 01 98.3%
  • Banco Santander 02 97.7%
  • BMO Capital Markets 12 97.2%

Professional Growth Opportunities

July 2026 Investment Banking

  • Evercore 01 99.4%
  • Moelis & Company 01 98.9%
  • Morgan Stanley 06 98.3%
  • Goldman Sachs 01 97.8%
  • JPMorgan 01 97.2%

Total Avg Compensation

July 2026 Investment Banking

  • Vice President (16) $429
  • Associates (46) $258
  • 3rd+ Year Analyst (8) $210
  • 2nd Year Analyst (23) $182
  • Intern/Summer Associate (14) $159
  • 1st Year Analyst (81) $150
  • Intern/Summer Analyst (73) $101
notes
16 IB Interviews Notes

“... there’s no excuse to not take advantage of the resources out there available to you. Best value for your $ are the...”

Leaderboard

1
redever's picture
redever
99.2
2
BankonBanking's picture
BankonBanking
99.0
3
Secyh62's picture
Secyh62
99.0
4
kanon's picture
kanon
99.0
5
CompBanker's picture
CompBanker
98.9
6
dosk17's picture
dosk17
98.9
7
GameTheory's picture
GameTheory
98.9
8
DrApeman's picture
DrApeman
98.9
9
Betsy Massar's picture
Betsy Massar
98.9
10
Jamoldo's picture
Jamoldo
98.8
success
From 10 rejections to 1 dream investment banking internship

“... I believe it was the single biggest reason why I ended up with an offer...”