The BBC reports that the steroid dexamethasone has been shown to reduce the risk of death by Covid-19.
This 'n' that
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Bill Spight
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Re: This 'n' that
OT, but good news.
The BBC reports that the steroid dexamethasone has been shown to reduce the risk of death by Covid-19.
The BBC reports that the steroid dexamethasone has been shown to reduce the risk of death by Covid-19.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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ez4u
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Re: This 'n' that
Banned for sports people, including mind-gamers of course!Bill Spight wrote:OT, but good news.
The BBC reports that the steroid dexamethasone has been shown to reduce the risk of death by Covid-19.
Dave Sigaty
"Short-lived are both the praiser and the praised, and rememberer and the remembered..."
- Marcus Aurelius; Meditations, VIII 21
"Short-lived are both the praiser and the praised, and rememberer and the remembered..."
- Marcus Aurelius; Meditations, VIII 21
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Bill Spight
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Re: This 'n' that
No point in hiding this.
Let Black be komonster, not only able to win the ko but able to keep fighting it until the ambient temperature is 0. Temperature 0 by area scoring is -1 by chilled area scoring. I.e., if you are komonster at territory scoring you don't have to win the ko until the dame stage; at area scoring you don't have to win the ko until the stage of filling territory or passing.
1) Territory scoring.
Result: 2 pts.
Result: 1 pt.
Result: 0
All of which means that the original territorial count is 1¼ and each play gains ¾ pt.
2) Chilled Area scoring, counting territory
Result: 3 pts.
Result: 2 pts.
Result: 1 pt.
Result: 0
Which means that the chilled area count after
- 
is 0, with reverse sente by Black gaining 1 pt. of territory.
Which means that the chilled area count after is 1; the position is ambiguous with local temperature 1.
Which also means that the original chilled area count is 2; the position is ambiguous with local temperature 1.
Let Black be komonster, not only able to win the ko but able to keep fighting it until the ambient temperature is 0. Temperature 0 by area scoring is -1 by chilled area scoring. I.e., if you are komonster at territory scoring you don't have to win the ko until the dame stage; at area scoring you don't have to win the ko until the stage of filling territory or passing.
1) Territory scoring.
Result: 2 pts.
Result: 1 pt.
Result: 0
All of which means that the original territorial count is 1¼ and each play gains ¾ pt.
2) Chilled Area scoring, counting territory
Result: 3 pts.
Result: 2 pts.
Result: 1 pt.
Result: 0
Which means that the chilled area count after
- is 0, with reverse sente by Black gaining 1 pt. of territory.Which means that the chilled area count after
is 1; the position is ambiguous with local temperature 1.Which also means that the original chilled area count is 2; the position is ambiguous with local temperature 1.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: This 'n' that
No point in hiding this, either.
This time let White be komonster.
1) Territory scoring.
Result: 1 pt.
Result: 2 pts.
Which means that the territorial count after
closing the corridor is 1½.
Result: 1¼.
This is ¼ pt. less than closing the corridor. As if we didn't know.
Result: 0
Result: 0
Which means that after in the corridor, the play in the corridor and the play in the ko are miai. Which means that the result after in the corridor is 0.
After, is ambiguous at temperature 1. Result: 0.
However,
could be at 3, gaining 1 pt. So correct play for is to enter the corridor.
All of which means that the territorial count of the original position is ¾ pt., with each play gaining ¾ pt.
2) Chilled area scoring.
Now, the temperature of the ko by itself is 1 when White is komonster, which is the maximum in the corridor by itself, so it makes sense to start with play in the ko. We try that first.
Result: 1¼ pts.
Result: 0
We know that
gains 1 pt., so the result after in the corridor is 1. So should fill the ko, as if we didn't know.
Result: 0.
Result: -1 pt.
After takes the ko, is ambiguous, so the result after is -1.
Putting it all together, the original chilled area count is ⅛, with each play gaining 1⅛.
This time let White be komonster.
1) Territory scoring.
Result: 1 pt.
Result: 2 pts.
Which means that the territorial count after
closing the corridor is 1½.Result: 1¼.
This is ¼ pt. less than closing the corridor. As if we didn't know.
Result: 0
Result: 0
Which means that after
in the corridor, the play in the corridor and the play in the ko are miai. Which means that the result after in the corridor is 0.After
, is ambiguous at temperature 1. Result: 0.However,
could be at 3, gaining 1 pt. So correct play for is to enter the corridor.All of which means that the territorial count of the original position is ¾ pt., with each play gaining ¾ pt.
2) Chilled area scoring.
Now, the temperature of the ko by itself is 1 when White is komonster, which is the maximum in the corridor by itself, so it makes sense to start with play in the ko. We try that first.
Result: 1¼ pts.
Result: 0
We know that
gains 1 pt., so the result after in the corridor is 1. So should fill the ko, as if we didn't know.Result: 0.
Result: -1 pt.
After
takes the ko, is ambiguous, so the result after is -1.Putting it all together, the original chilled area count is ⅛, with each play gaining 1⅛.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: This 'n' that
On presentation
BTW, for this problem I tried the idea of indicating possible (later, actual) territory and potentially capturable (later, captured) stones. Was doing so a help or an annoyance or distraction?
BTW, for this problem I tried the idea of indicating possible (later, actual) territory and potentially capturable (later, captured) stones. Was doing so a help or an annoyance or distraction?
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: This 'n' that
On the calculation of variations
As my readers know, I don't usually say much about the conscious calculation of variations. I usually mention seeing, which is the conscious result of unconscious calculation. Seeing is not the same as having a so-called policy network, although seeing, like conscious calculation, depends upon the choice of which plays to explore.
But recently I have gotten interested in taking another look at human calculation of variations. Conscious calculation is severely limited by the size of human cortical workspace, so pretty much has to be based on depth first search.
Part of this interest has been inspired by a couple of topics here on Life in 19x19. One is Knotwilg's topic, Complexity as width x depth ( https://www.lifein19x19.com/viewtopic.php?f=15&t=17682 ). Another is BadukDoctor's topic, Daily life and death training ( https://www.lifein19x19.com/viewtopic.php?f=12&t=17284 ). To quote jlt about the latter:
One way of combining depth first search with exploration is iterative deepening depth first search. I.e., reading each option to depth one, then, if a solution is not found, reading each option to depth two, etc. AFAIK, nobody has actually suggested that humans use that for game tree search, but I thought I'd take a look.
Let me create the file for iterative deepening.
As my readers know, I don't usually say much about the conscious calculation of variations. I usually mention seeing, which is the conscious result of unconscious calculation. Seeing is not the same as having a so-called policy network, although seeing, like conscious calculation, depends upon the choice of which plays to explore.
But recently I have gotten interested in taking another look at human calculation of variations. Conscious calculation is severely limited by the size of human cortical workspace, so pretty much has to be based on depth first search.
Part of this interest has been inspired by a couple of topics here on Life in 19x19. One is Knotwilg's topic, Complexity as width x depth ( https://www.lifein19x19.com/viewtopic.php?f=15&t=17682 ). Another is BadukDoctor's topic, Daily life and death training ( https://www.lifein19x19.com/viewtopic.php?f=12&t=17284 ). To quote jlt about the latter:
OC, reading to the end makes use of depth first calculation, and trying other moves emphasizes exploration. The idea is not just to solve a problem, but to understand it thoroughly.jlt wrote:I like this series (as well as other videos of BadukDoctor). Not only he shows various techniques that occur in capturing races and life-and-death problems, but also he illustrates quite well his recommended method of practicing go problems: read all variations until the end even if they don't seem to work; try other moves even if we found a way to live or kill.
One way of combining depth first search with exploration is iterative deepening depth first search. I.e., reading each option to depth one, then, if a solution is not found, reading each option to depth two, etc. AFAIK, nobody has actually suggested that humans use that for game tree search, but I thought I'd take a look.
Let me create the file for iterative deepening.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: This 'n' that
Progris Riport
Well, trying to make an SGF file for iterative deepening as a whole was not a good idea. I got lost, and if I had not known the solution ahead of time I would not have know it afterwards. Easier just to do the calculations in my head.
No results until depth 3, so here is the depth 3 file for depth first search.
Hmmm. It seems that I accidentally posted this. Let me continue.
Psychological notes.
1) Stopping after 3 moves went against the grain, unless the position was resolved.
2) Deliberately playing bad moves, except at move 1, was even worse. OC, in real life, moves we think are bad are not necessarily so. That holds for both bots and humans.
OC, raw beginners may not share these feelings.
Technical note.
Noticing transpositions is useful. One way to help do so is to keep the same order of moves for each player. That way, it is easy to tell if the order is reversed. That will usually indicate a transposition.
Possible go lessons.
I only used a 9x9 board for convenience, so I am going to leave the diagrams as 19x19.
is a likely mistake. We can only say likely at this point, because White dying is the expected result of the problem. OC, a 5 kyu is not going to play , but I am taking the viewpoint of a raw beginner, for whom this is a lesson.
Transposition.
Again, is a likely error.
Transposition.
Ditto.
Transposition.
Aside from the likelihood that is a mistake in these variations, can we draw any other conclusions?
lies on each of the 
points twice, but never on the 
points. Which suggests that the points are typically good points for White.
Note also that is never adjacent to . Which suggests that playing adjacent to may be a good idea.
What about?
lies on each point twice, on each 
point once, and on the point never. Which suggests that the points are good for Black and the point is bad for Black.
Well, trying to make an SGF file for iterative deepening as a whole was not a good idea. I got lost, and if I had not known the solution ahead of time I would not have know it afterwards. Easier just to do the calculations in my head.
No results until depth 3, so here is the depth 3 file for depth first search.
Hmmm. It seems that I accidentally posted this.
Let me continue.Psychological notes.
1) Stopping after 3 moves went against the grain, unless the position was resolved.
2) Deliberately playing bad moves, except at move 1, was even worse. OC, in real life, moves we think are bad are not necessarily so. That holds for both bots and humans.
OC, raw beginners may not share these feelings.
Technical note.
Noticing transpositions is useful. One way to help do so is to keep the same order of moves for each player. That way, it is easy to tell if the order is reversed. That will usually indicate a transposition.
Possible go lessons.
I only used a 9x9 board for convenience, so I am going to leave the diagrams as 19x19.
is a likely mistake. We can only say likely at this point, because White dying is the expected result of the problem. OC, a 5 kyu is not going to play , but I am taking the viewpoint of a raw beginner, for whom this is a lesson.Transposition.
Again,
is a likely error.Transposition.
Ditto.
Transposition.
Aside from the likelihood that
is a mistake in these variations, can we draw any other conclusions?In the six variations where White dies,Samuel Butler wrote:Life is the art of drawing sufficient conclusions from insufficient premises.
lies on each of the points twice, but never on the points. Which suggests that the points are typically good points for White. Note also that
is never adjacent to . Which suggests that playing adjacent to may be a good idea.What about
? lies on each point twice, on each point once, and on the point never. Which suggests that the points are good for Black and the point is bad for Black.The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: This 'n' that
Iterative deepening, continued
The depth 4 search was interesting. And productive. I followed the heuristic of playing next to , if possible, and otherwise playing on one of points of the depth 3 search. That reduced the work quite a bit by frequently letting White live on move 4 without much search. Below is the depth 4 SGF file.
The depth 4 search revealed Black's first move. It did so by proving that White lives after each of the other first moves. The logic is simple. If, after a Black move, White has a reply that makes White live, the Black move fails to kill (or make ko, if that is the outcome). And that White move makes life if it does so by making two eyes or a seki, or if every Black reply allows White to live.
After, lives because 
can make life after 
on each of the points.
Ditto.
Ditto.
After Black has only 2 points for , and White makes life after each one. may not be best play, but it makes life with . (OC, it makes life itself, but I am taking the viewpoint of a rank beginner.)
So Black's first move is the crawl along the edge at A-17. We have already eliminated two of White's replies at depth 3, and then after each remaining , Black has only one good reply. That leaves us with the following possibilities for depth 5.
White dies in all four cases.
Playing next to was a good rule of thumb.
The depth 4 search was interesting. And productive. I followed the heuristic of playing
next to , if possible, and otherwise playing on one of points of the depth 3 search. That reduced the work quite a bit by frequently letting White live on move 4 without much search. Below is the depth 4 SGF file. The depth 4 search revealed Black's first move. It did so by proving that White lives after each of the other first moves. The logic is simple. If, after a Black move, White has a reply that makes White live, the Black move fails to kill (or make ko, if that is the outcome). And that White move makes life if it does so by making two eyes or a seki, or if every Black reply allows White to live.
After
, lives because can make life after on each of the points.Ditto.
Ditto.
After
Black has only 2 points for , and White makes life after each one. may not be best play, but it makes life with . (OC, it makes life itself, but I am taking the viewpoint of a rank beginner.)So Black's first move is the crawl along the edge at A-17.
We have already eliminated two of White's replies at depth 3, and then after each remaining , Black has only one good reply. That leaves us with the following possibilities for depth 5.White dies in all four cases.
Playing
next to was a good rule of thumb. The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: This 'n' that
Discussion of the problem and solution process
My guess is that this is around a 5 kyu problem. OC, a 5 kyu might well overlook the kill in an actual game, but given the position as a problem, could probably solve it in a reasonable amount of time. Hmmm. Maybe it is a 7 kyu problem.
Before posting this I went back and took another look at BadukDoctor's treatment of this problem. He was quite thorough, with attention to detail, and showed most of the same variations as I put in the depth 4 file. The problem material available in books and magazines when I was learning go usually showed only a few variations, and if I found the mainline solution I was satisfied. But some years ago I ran across Mr. K's site, http://mrkigo.sakura.ne.jp/ksikatuindex.html , where he goes into great detail about introductory life and death positions. There was a lot that I had never thought about, lessons that I had not learned at that stage in my development, but in retrospect I wish that I had learned back then. I became an instant fan of Mr. K's thoroughness.
Let's take a look at one variation.
Now, for a 5 kyu, or a 7 kyu, or even most DDKs, is silly. However, to prove that lives, it is necessary to show that does not kill. And, from the standpoint of learning to calculate variations, it is good to practice thoroughness and attention to detail.
At the same time, however, . . .
also lives, making 3 and 4 miai for life. It is not necessary, from the standpoint of solving the problem, and, hence, of calculating variations to that end, to show more than one way for to make life. In my depth 4 file I showed that this lived, and did not look for another to live. That would have been overkill. One advantage of iterative deepening, or at least, reading to a certain depth, is that you achieve thoroughness systematically, not haphazardly.
As most of my readers know, I am not a fan of the advice, for amateurs, anyway, not to look at the answers. Even Cho U, a modern master of tsumego, has revealed that as a kid he looked at the answers. Instead I have advised people to set aside a certain length of time, 30 seconds, one minute, two minutes, 15 minutes, whatever, to solve a problem, and then look at the answer. OC, that's just the first time around. It is necessary to overlearn the solution. Now I wonder if it is better to set a certain depth to read, and then stop. This is a depth 5 problem. You won't solve it at depth 4. But you could start off reading systematically at depth 4, at which point the rest is obvious.
This problem has illustrated the importance of good heuristics. Let me add other learning, as well.
For me, the sequence, - is a chunk that makes an eye. I therefore do not need to look at other options for . The chunk is indivisible.
It is also obvious to me that makes a second eye. Now, it takes two more moves for that eye to be closed, but, as we say, the three points, along with the adjacent White stones, form an eye space with the value of one eye for White. Informally, White has an eye. Now, that is something that maybe most 5 kyus do not know, but experienced tsumego solvers know that White can make an eye in that space, even if Black goes first. By simple arithmetic Black's play takes away one point and so does White's reply, but that leaves one open point for the eye.
OC, I did not rely upon such knowledge in illustrating iterative deepening, but in actuality it is quite useful.
My guess is that this is around a 5 kyu problem. OC, a 5 kyu might well overlook the kill in an actual game, but given the position as a problem, could probably solve it in a reasonable amount of time. Hmmm. Maybe it is a 7 kyu problem.
Before posting this I went back and took another look at BadukDoctor's treatment of this problem. He was quite thorough, with attention to detail, and showed most of the same variations as I put in the depth 4 file. The problem material available in books and magazines when I was learning go usually showed only a few variations, and if I found the mainline solution I was satisfied. But some years ago I ran across Mr. K's site, http://mrkigo.sakura.ne.jp/ksikatuindex.html , where he goes into great detail about introductory life and death positions. There was a lot that I had never thought about, lessons that I had not learned at that stage in my development, but in retrospect I wish that I had learned back then. I became an instant fan of Mr. K's thoroughness.
Let's take a look at one variation.
Now, for a 5 kyu, or a 7 kyu, or even most DDKs,
is silly. However, to prove that lives, it is necessary to show that does not kill. And, from the standpoint of learning to calculate variations, it is good to practice thoroughness and attention to detail. At the same time, however, . . .
also lives, making 3 and 4 miai for life. It is not necessary, from the standpoint of solving the problem, and, hence, of calculating variations to that end, to show more than one way for to make life. In my depth 4 file I showed that this lived, and did not look for another to live. That would have been overkill. One advantage of iterative deepening, or at least, reading to a certain depth, is that you achieve thoroughness systematically, not haphazardly. As most of my readers know, I am not a fan of the advice, for amateurs, anyway, not to look at the answers. Even Cho U, a modern master of tsumego, has revealed that as a kid he looked at the answers.
Instead I have advised people to set aside a certain length of time, 30 seconds, one minute, two minutes, 15 minutes, whatever, to solve a problem, and then look at the answer. OC, that's just the first time around. It is necessary to overlearn the solution. Now I wonder if it is better to set a certain depth to read, and then stop. This is a depth 5 problem. You won't solve it at depth 4. But you could start off reading systematically at depth 4, at which point the rest is obvious. This problem has illustrated the importance of good heuristics. Let me add other learning, as well.
For me, the sequence,
- is a chunk that makes an eye. I therefore do not need to look at other options for . The chunk is indivisible. It is also obvious to me that
makes a second eye. Now, it takes two more moves for that eye to be closed, but, as we say, the three points, along with the adjacent White stones, form an eye space with the value of one eye for White. Informally, White has an eye. Now, that is something that maybe most 5 kyus do not know, but experienced tsumego solvers know that White can make an eye in that space, even if Black goes first. By simple arithmetic Black's play takes away one point and so does White's reply, but that leaves one open point for the eye. OC, I did not rely upon such knowledge in illustrating iterative deepening, but in actuality it is quite useful.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Tryss
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Re: This 'n' that
All in all, I don't see how iterative deepening help in these kind of situations compared to a Depth-first search with backtracking.
To truly solve a problem like this, you need to fully explore all the branch of the tree, it doesn't matter in what order.
To truly solve a problem like this, you need to fully explore all the branch of the tree, it doesn't matter in what order.
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Bill Spight
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Re: This 'n' that
You don't need to fully explore all branches of the tree. Thank goodness!Tryss wrote:All in all, I don't see how iterative deepening help in these kind of situations compared to a Depth-first search with backtracking.
To truly solve a problem like this, you need to fully explore all the branch of the tree, it doesn't matter in what order.
There is a whole branch of computer science literature aimed at improving upon brute force depth first search. This is a small problem, with only 5 possibilities for the first move. 4 of them are wrong. With bad luck you could explore all 4 failing branches before hitting upon the path to the solution. Iterative deepening assures that you will always go down the right path at every level of depth. You won't spend a lot of time on failing paths at greater depths than the shallowest solution.
It turns out that this example is not a good one to show the advantage of iterative deepening, because the solution is at depth 5.
But that was not my purpose. I meant to show a way to achieve systematic thoroughness in the calculation of variations. And as I said, I don't know of anyone who actually recommends it for humans in actual play.
Last edited by Bill Spight on Mon Aug 10, 2020 6:18 am, edited 2 times in total.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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John Fairbairn
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Re: This 'n' that
My take on what Bill was suggesting is this:All in all, I don't see how iterative deepening help in these kind of situations compared to a Depth-first search with backtracking.
Humans (amateurs at any rate) have a built-in propensity to do a depth-first search in any situation. When fighting wild animals or growing corn, that may be biologically the best policy, but in go it is full of pitfalls. The commonest - and I don't believe anyone reading this forum has never fallen in this pit - is to find a quick answer and to stop there. Turn the page and the pro explains various other wrinkles such as ko that you did not even look for.
Iterative deepening (perhaps not the ideal term here, as it tempts people to read computer science into it) seems a cheap way to ensure all (or most) alternatives are looked at.
You could maybe get the same effect by backtracking, but the human brain seems to find it harder to keep track that way.
Cue Irish joke which I'm sure Bill will appreciate: American tourist lost in Portlaoise asks native how to get to Dublin. Wise old native sucks on pipe and says, "well, if I was you I wouldn't start from here."
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Bill Spight
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Re: This 'n' that
American version:John Fairbairn wrote:Cue Irish joke which I'm sure Bill will appreciate: American tourist lost in Portlaoise asks native how to get to Dublin. Wise old native sucks on pipe and says, "well, if I was you I wouldn't start from here."
But first, an aside. I read years ago that, in one form or other, one of the most widespread jokes across human cultures is the riddle, "Why did the chicken cross the road?"
Anyway, in the American version, a tourist is lost in Maine and asks an elderly gentleman how to get to, let us say, Boston. The elderly gentlman, who also smokes a pipe, takes it out of his mouth and says, "You can't get theah from heah."
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Tryss
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Re: This 'n' that
So you will stop once you found a solution? I believed that the goal was fully reading all the variations, and not just finding one line that works.Bill Spight wrote: This is a small problem, with only 5 possibilities for the first move. 4 of them are wrong. With bad luck you could explore all 4 failing branches before hitting upon the path to the solution. Iterative deepening assures that you will always go down the right path at every level of depth. You won't spend a lot of time on failing paths at greater depths than the shallowest solution.
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Bill Spight
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Re: This 'n' that
As I said, my goal here was to illustrate a method to achieve systematic thoroughness for study and training purposes. In this case there is little difference between brute force depth first search and iterative deepening, because the solution is at close to maximum depth. Here is a problem where the maximum depth is around 13, I think, maybe even 15.Tryss wrote:So you will stop once you found a solution? I believed that the goal was fully reading all the variations, and not just finding one line that works.Bill Spight wrote: This is a small problem, with only 5 possibilities for the first move. 4 of them are wrong. With bad luck you could explore all 4 failing branches before hitting upon the path to the solution. Iterative deepening assures that you will always go down the right path at every level of depth. You won't spend a lot of time on failing paths at greater depths than the shallowest solution.
I peeked at the solution, and it has a depth of around 6 or 7. Even if you didn't have the bad luck to pick the correct play last, you could spend a very long time on failing paths to relatively great depths.
And since they are erroneous paths, how much light would they shed on the actual problem? 
It's not helpful to go too far afield. The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.