Abu Bakr bin Yahya al Suli and his diamond mansuba
Abu Bakr Muhammad bin Yahya al-Suli [أبو بكر محمد بن يحيى الصولي // you also find him "as-Suli" // in wiki] (880 Gorgan, Iran - 946 Basra, Iraq) among others was a great shatranj player and composer. His name survived for many centuries after, as a legendary shatranj master.
Statue in Ashgabat, Turkmenistan, found via russian wiki
A beautiful story around his shatranj course is about a mansuba [shatranj study], the one called al-Suli's diamond.
H. J. R. Murray in his History of Chess (1913), p. 314, describes this mansuba:
"No122. AH 137: C 26.
Green: Kb3, Qc3 - Red: Ke4, Q omitted in both MSS. // Red plays - Green wins.
The solution begins : "If Red were to play he would win after three moves. Black has nothing except to go to his Farzin's 4th [d5], a Faras-move from the Red Farzin [N-move distance], for every square other than this to which he can move loses. The Red Shah mounts to his Faras 4th [b4]. Black has nothing except his Farzin's 3rd [d6]."
The solution is then dismissed, partly because it is lengthy, and partly because as-Suli was extremely proud of it. He goes on to say: "This is very old, yet neither al-'Adli nor any one else has said whether it is drawn or can be won. Nor has any one interpreted it, or pointed (diagrammed) it because of its difficulty. There is no one on earth who has solved it unless he was taught it by me. I have never learnt that there was any one before, for if any one had solved it, he would either have written down the solution, or have taught it to some one else." This is the word of as-Suli."
The 122 position: Big shatranj pieces are the kings, smaller are the Farzins
Although the black's Q position isn't mentioned, we know her existence from another mansuba [check below] and the only right place is Qa1, so the stipulation "...Black has nothing except to go to his Farzin's 4th [d5]..." to be fulfilled.
[Unfortunately I couldn't find an online copy of the mentioned in Murray manuscripts (AH = MS. Abd-al-Ḥamīd I, Constantinople, no. 560 & C = MS. Khedivial Lib., Cairo, Muṣṭafa Pasha, no. 8201) and so the earliest reference of this mansuba I've found is Murray's book 
].
Must be reminded some shatranj rules:
- King moves as in chess.
- Farzin [Q] moves only 1 square diagonally.
- Win comes with checkmate but also with the bare king rule: that is to leave the opponent's army without any other piece but the king.
- Unless, in the next move the opponent, also, can capture your last piece. Then it's a draw.
- Pawns promote only to Farzin.
This mansuba seems to have been remained unsolved for centuries. In 1980s some tries restarted. David Hooper and Ken Whyld published a solution in their Oxford Chess Companion (1986) but seemed to be imperfect, although was based on the indicated by Suli "2. Kb4".
Specifically I've found a variation indicated as dead end by Hooper and Whyld "1... Kd5 2. Kb4! Kd6 3. Kc4 Ke5 4. Fb4 Kd6 5. Kc3! Kd5 6. Kc2 Kc4 7. Fa3 Kb5 8. Kb1 (distant opposition) Ka4 9. Ka2 (zugzwang)".
But in 1993, during a chess conference of Max Euwe Center in Amsterdam, Yuri Averbach [besides his great chess career, was also known for his speciality in older games], announced that he had found a solution! [check The Immortal Game by David Shenk (2007), richer maybe narrative is found in The Human Comedy of Chess by Hans Ree, that is a translation of the original Schitterend schaak (1997)].
The solution goes:
1. Kb4 Kd6 2. Kc4 Ke6 3. Kd4 Kf6 4. Kd5 Kf7 5. Ke5 Kg7 6. Ke6 Kg8 7. Kf6 Kh8 (this was the position that Averbakh had noticed in an Arabian manuscript // check below too) 8. Kg6 Kg8 9. Qd2 Kf8 10. Qc1 Ke7 11. Kf5
(6... Kf8 7. Kd6 Ke8 8. Kc6 Kd8 9. Kb6 Kc8 10. Kc5 Kd7 11. Kb5 Kc7 12. Kc4 Kd6 13. Kb4 Ke5 14. Ka3 Kd5 15. Kb3)
I hope that this gif with the main variation is helfpful
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Averbach probably had checked and other Suli's sayings.
Specifically Murray [p. 313] writes for an other mansuba:
"No 112: AH 127 - C113 - RAS 38 - V 42.
Red: Kh8, Qa1 - Green: Kf6, Qc3 // Green plays and wins.
1. Kg6 Kg8 2. Qd2 Kf8 3. Qc1, Ke7 & etc. The text in AH and V ends with the note "There is also a problem without solution of Q vs Q, which is the 10th after this, which resembles this." See No. 122, which is in the right place in AH, but occurs nowhere in V."
That's probably how we know what manuscript Averbach saw and the sure existence of Farzin in No122.
The 112 position
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Averbach followed Suli's sayings and found an according to Suli solution but maybe long.
A proposed shorter solution
I've tried to check this mansuba, taking also in account Hooper & Whyld, but mainly a key move, Qd2. Qd2 maybe can be played earlier than the Suli's indications. [check also this link with solution // in the previous link Qd2 (or Fd2) is proposed on the 5th move].
Here's a continuation I've made, with much doubt, but I think it's valid.
[this solution I've tried, proved incorrect: check comments ~ so if you want to skip it press here]
Key: keep sufficient distance between white Q and black K.
[I use olive-popeye software for problems, but I couldn't find any fairy stipulation of bare king (or lone king) or anything similar. So this solution is 100% human and must be checked... I hope by some reader].
1... Kd5 2. Qd2 Ke4 (aiming to reach d1 on time)
2... Kd4 3. Kc2 Kc4 (or Ke4) 5. Qc1 (and whatever black plays 6. Kb1 7. Kxa1, as black K needs at least 3 plies to take white's Q)
3. Kc3 Kf3
3... Kf4 4. Kc2 Kf3 (if 4... Ke4 5. Qc1) 5. Qc3 Ke3 6. Qb4 Kd4 7. Kb3 (same as main line)
4. Kc2 Ke2 5. Qc3 Ke3 6. Qb4 Kd4 7. Kb3 Kd3 8. Qa3 Kd2 9. Ka2 Kc2 10. Kxa1
Generally white K is used as a center for opposition and white Q is going the opposite way of black K, as Hooper and Whyld tried. You think it's a good solution? Is there a cook, inaccuracy, whatever??? No software used to check, so if it's false forgive me...
This was added on 07/09/2018 as a better way of presentation
This is the main idea of the solution
[EDIT 19.08.2018: Just noticed that in the GIF I write in one variation 5. Kc1 ~on right~ while I show the Q [farzin] moving. Obviously the correct is 5. Qc1.]
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Besides these, as you've noticed, the farzins of the above mansubat, are of the same colour, that means that one is a pawn promoted and possibly black by a rook pawn.
A similar position I've found in Murray's book is no1 [p. 306], described as a position of al Adli's work and criticized by Suli. As it seems the endgame positions with last pawns, that had been promoted, really concerned the shatranj masters.
The 1 position [here the left down square is h8]
Murray writes:
"No1: AH 9 - C 47 - BM 149=186 - Y 14 - Al. 7 = 13
Red: Ke4, Qh8 - Green: Ke7, Qh6 // Green plays and wins
Al Adli's solution was 1. Ke6 Kf4 2. Kf6 Kg4 3. Kg6 Kh4 4. Qg5+ Kg4 5. Qf6 Kf4 6. Kf7 Kf5 7. Qe7 Ke5 8. Kg8 Ke6 9. Qf8 Kd7 loses (by Bare King). This is said to be in 18 moves [plies meant]. As-Suli shortened it to 8 moves by 1. Kf8 Kf5 2. Kf7 Kg4 3. Kg8 Kh5 4. Kh7 and loses by Bare King. BM only gives al-Adli's solution. Al. only as-Suli's. Cf. for the ending Q vs Q, Nos. 112, 132. and 277."
The Suli's solution shows that he knew well how to use kings' opposition.
Happily I've found an arabic manuscript showing this position. 
From manuscript Kitab fi al shaṭranj [كتاب في الشطرنج ومنصوباته وملحه]
[in Murray, p. 173, (3. BM = MS. British Museum, Arab. Add. 7515 (Rich)), "...There is nothing in the MS. to show the name of its author, but he has made liberal use of al-'Adll's work and quotes from al-Lajlaj with approval. As-Suli is on the whole ignored." // So probably here is shown al Adli's solution.] [reference forgotten : date: 655/1257 in Qatar Digital Library].
And for arab readers, here're 2 pages with the diagram. If possible, please share a translation. It has to be poetic... [image is large enough, open it in a new tab].
[edit: 11/07/2018, just 13 hours after first post...
Sometimes some things escape one's attention...
Here's a position where the farzins are of the opposite colour [as from the initial position] and the game is drawn, like the usual result of modern games with bishops of different colour in the end .
Murray writes [p. 322]:
"No 277: BM 207.
Red: Kf6, Qa1 - Green: Ke3, Qe4.
Red plays; drawn: 1 Ke5, Qf3!"
From the same manuscript as above
...end of edit]
Some plus reference links
I hope you've enjoyed it, as I did...
