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Tennis Teaser: Newsletter Challenge (October 2019)

Posted September 30, 2019 5:01 PM
Pathfinder Tags: challenge question tennis

This month's IEEE GlobalSpec Newsletter Challenge is:

You've been granted magical tennis powers, which allowed you to reach the US Open finals against Rafael Nadal. The powers, however, can't last the entire match. At which score would you prefer them to wear off to maximize your chance of winning?

And the answer is:

This question comes from the archives of Dartmouth math professor Peter Winkler. Winkler gives several solutions, in order of favorability to you winning the match:

-Let the set score be 2-0 in your favor in the best-of-five match, ahead 5-0 in game score and leading 40-love in the sixth game. This gives you three chances to win match point until the game score is tied 40-40, at which point Nadal could begin to beat your powerless self back.

-Even better, let the set score be 2-0 in your favor, tied 6-6 in game score in the third set, and leading 6-0 in the first-to-seven tiebreak point. This gives you six chances to win the tiebreak match point.

-A dubious but still possible answer would be a score of 6-0, 7-6 (1,000-998), 6-6 (6-0). In this case you have won the first set easily, won the second set by an absurdly long tiebreaker involving almost 2,000 games (in which case Nadal has completely exhausted himself), and are now leading 6-0 in the third set tiebreaker. In other words, you have six chances to win against a world-class but completely exhausted player.

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#1

Re: Tennis Teaser: Newsletter Challenge (October 2019)

09/30/2019 7:02 PM

6 - 0

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#2
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Re: Tennis Teaser: Newsletter Challenge (October 2019)

09/30/2019 8:36 PM

...and 40 love

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#3

Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/01/2019 9:22 AM

Is this like a grade school "gotcha!" question? For example: A ladder is hanging over the side of a boat, with the lower end submerged in water. There are 6 rungs showing and the rungs are 1' apart. If the water level rises 2' to high tide, how many ladder rungs will then be showing? Presumably, in the imaginary "tennis teaser" scenario, since I have magical powers, my opponent will have no score at the time my powers wear off, and so if those powers can't last the entire match, and I wish to maximize my chance of winning, I would choose to lose my magical powers when I was one point from victory. My chance of victory would be further enhanced because, by then, my opponent would be struggling with loss of confidence. If there is a knotty problem to solve here, I don't see it, which is why I anticipate a gleeful "gotcha!" following this post.

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#9
In reply to #3

Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/01/2019 11:23 AM

It's not really a "gotcha," although to get the best mileage out of the question it helps to know tennis scoring. There are a few possible scores you could choose that would best hedge your chances.

https://en.wikipedia.org/wiki/Tennis_scoring_system

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#19
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Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/03/2019 7:22 PM

Wikipedia covers tennis scoring OK, but it seems there is nothing regarding magical powers...

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#4

Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/01/2019 9:37 AM

Unlike American football, tennis is an untimed sport where the game can and has turned around at the last moment for a player. Tara Moore did accomplish such a comeback this past April. Knowing my athletic skills the only way I could get a point let alone defeat Mr. Nadal in his sport is only with the aid of magical powers thus my only hope is to be the loser to his epic comeback. I would want these powers to end after achieving 6-0 6-0 5-0 matchpoint advantage Redfred. My collapse after this would be so spectacular with a final score of 6-0 6-0 5-7 0-6 0-6. Cheating on my part would certainly be suspected.

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#10
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Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/01/2019 12:40 PM

In the scenario you describe, you can beat Nadal without violating the prescribed terms of the imaginary tournament. You need one more point, so ask the genie in the bottle to allow you to keep your superhuman tennis powers until midway through your final, unreturnable serve to Nadal. More precisely, ask to keep those powers until the micro-moment after the ball has lost contact with your racket, such that your special powers will be gone before the ball contacts the court surface on the other side of the net and before the serve is called good and within bounds. Thus, you lose your powers before the end of the tournament, with the outcome still unsettled, but with the best possible chance of victory (the possibility of an asteroid strike (for example) while the ball is still in flight retains the required uncertainty of outcome).

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#11
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Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/01/2019 1:58 PM

I thought of another possibility on the same theme. The exact same score but Nadal is serving his second serve. If the ball successfully falls in bounds on my side of the court then Raphael still gets his spectacular comeback. If he doesn't...

In either scenario, I immediately retired from sports after the match. That is if I survive the rest of the match.

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#14
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Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/02/2019 2:32 AM

The challenge asks "at which score" (not "at which moment"). So, if you have won 2 sets and you have 5-0 and 40-0 in the last one, you have 4 chances that either Nadal makes a mistake or you have a lucky shot and you win. But the best scenario is the one in which in the last set the score is 6-6 and in the tiebreak you have 6-0 - in this case you have 6 chances to win.

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#16
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Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/02/2019 9:25 AM

To be a tiresome word stickler: The challenge states that my magic powers will not last until the end of the tournament. It does not state that those magic powers will disappear the instant my preferred score is achieved, nor is there any implication that this will occur. Therefore, the challenge terms are satisfied if my magic powers disappear at any time between when the preferred score is achieved, and the end of the tournament. Since that moment is a variable, falling outside the terms of the challenge, I assume the liberty of choosing that moment.

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#5

Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/01/2019 9:42 AM

To be the best person I can be in this situation, I would want my powers to last thru many sets until the final victory set and up until the last serve by my opponent under tied up conditions of a very close match that comes right up to this last chance for my opponent. Then I would want my powers to wear off and the one who has put in all the real hard work and training to receive what is truly theirs. I will although thoroughly enjoy every minute of the contest until then.

R3 = Retired and on my 3rd round in life.

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#6

Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/01/2019 9:57 AM

I have to post a simultaneous complaint and compliment for this challenge question.

My complaint is that this question asks for our preference. Our preference is our preference. There is no right or wrong to any preference unless one lies about the preference. A preference is not a challenge. Achieving a preference might be a challenge.

Despite this question being erroneously posted as a challenge question, I have to compliment the nature of the question itself. I look forward to seeing how people respond to this question.

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#8
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Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/01/2019 11:15 AM

...thanks???

As the Challenge Question poster I agree with both your assessments. This month's question is a little different than past ones, and in this case some "preferences" will be more objectively correct than others. I like questions with more than one correct answer -- they encourage more discussion than just working out a math or physics problem.

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#7

Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/01/2019 11:14 AM

Well to assure a win for the home team, you would probably want to exhaust your opponent with a long tedious match until he couldn't go on, and you win by default...

Isner–Mahut match at the 2010 Wimbledon Championships

..."In total, the match took 11 hours, 5 minutes[2] of play over three days, with a final score of 6–4, 3–6, 6–7(7–9), 7–6(7–3), 70–68 for a total of 183 games. It remains by far the longest match in tennis history, measured both by time and number of games. The final set alone was longer than the previous longest match.

Both players broke numerous Wimbledon and tennis records, including each serving over 100 aces, with the match being referred to as "the endless match".[3] A rule change instigated for the 2019 Championships introducing a tie break in the fifth set means that the Isner-Mahut match will remain the longest match in Wimbledon tournament history in terms of games played, provided this change remains in place."...

...

....but they changed the rules, so you have to win at least one point....probably your only hope is that he screws up ...

https://en.wikipedia.org/wiki/Isner%E2%80%93Mahut_match_at_the_2010_Wimbledon_Championships

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#12

Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/01/2019 11:38 PM

You will never win, at whatever stage, your magical powers wear off, since you are no where near Nadal's prowess at any stage, without them.

That's it.

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#13

Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/02/2019 1:16 AM

I would give my magical powers to my opponent, for if I actually needed them, I would of never entered into such a contest.

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#15

Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/02/2019 5:32 AM

I assume the magical powers are restricted to your physical ability to play your part rather than metaphysics to control the trajectory of your opponents ball.

But even so, match point must be the pivot where it can all go wrong for you - and to my mind if you got to match point by 'magic' I would hold out much hope for you to win.

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#17

Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/02/2019 10:20 AM

I would like the magic to last long enought for a chance to be on the same court as Rafael Nadal. The initial score would be Love - Love. After that, he would whomp my butt. But, for a moment anyway, I would have earned the merit of being good enough to qualify to play Rafael Nadal. And, until the first serve, we would be tied.

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#18

Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/02/2019 9:36 PM

At the end of the third set. You win 3 of the 5 sets, you got it sown up. As Redfred said.

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#20

Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/08/2019 9:49 AM

Several possible answers are posted.

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#21

Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/08/2019 9:51 AM

Key point:

"Which allowed you to reach the US Open finals against Rafael Nadal"

This is the past tense so....

Did I win?

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#22
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Re: Tennis Teaser: Newsletter Challenge (October 2019)

10/11/2019 2:17 PM

NO, you got a high velocity tennis ball to the nads and had to drop out....obviously effected your memory as well...There's always next year...

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