# No.900 (PAP)

 No.900 Petko A. Petkov (Bulgaria) Original Problems, Julia’s Fairies – 2015 (II): July – December    →Previous ; →Next ; →List 2015(II) Please send your original fairy problems to: julia@juliasfairies.com

No.900 by Petko Petkov – Five times Sentinels-duel between White and Black; task. The problem composed in the memory of C. K. Ananthanarayanan, the inventor of Sentinels. (JV)

Definitions:

Sentinels: When a piece (Ks included but not pawns) moves, a pawn of the same colour appears on the vacated square unless that square is on the first or eighth ranks or there are 8 pawns of that colour on the board already.

LEO(LE): Chinese piece operating along Queen lines: moves as Queen, but captures only by hopping over a hurdle to any square beyond.

RAO(RA): Chinese piece operating along the lines of Rose: moves as Rose, but captures only by hopping over a hurdle to any square beyond.

Rose(RO): (1,2) Octagonal Rider (extents the move of the Knight on a circular path e.g. a4-b6-d7-f6-g4-f2-d1-b2 or a4-c5-e4-f2).

Kangaroo(KA): Moves along Queen-lines over 2 hurdles (which may or may not stand on adjacent squares) to the square immediately beyond the second hurdle. A capture may be made on arrival, but the hurdles are not affected.

Rose-Kangaroo(RK): Moves as Kangaroo but along Rose lines only.

 No.900 Petko A. Petkov Bulgaria original – 23.09.2015 In the memory of C.K.Ananthanarayanan! Solutions: (click to show/hide) white ka2 Rc4 se4 Leb8 Bd7 pd3d4 black kd5 Qc1 RAd2 RTb3 hs#2                                         (7+4) b) LEb8→g4 ; c) Bd7→f5 d) LEb8→a8 ; e) Leb8→b4 Sentinels RAO d2; LEO b8 Rose-Kangaroo b3 a) 1.LEb8-e5 RAd2-f3[+bPd2] 2.LEe5-g5[+wPe5]+ RKb3*g5[+bPb3] # b) wLEb8-->g4 1.LEg4-e6 [+wPg4] RAd2-g5[+bPd2] 2.LEe6-f7[+wPe6]+ RKb3*f7[+bPb3] # c) wBd7-->f5 1.LEb8-d6 RAd2-f7[+bPd2] 2.LEd6-d8[+wPd6]+ RKb3*d8[+bPb3] # d) wLEb8-->a8 1.LEa8-c6 RAd2-d8[+bPd2] 2.LEc6-b7[+wPc6]+ RKb3*b7[+bPb3] # e) wLEb8-->b4 1.LEb4-c5 [+wPb4] RAd2-b7[+bPd2] 2.LEc5-a5[+wPc5]+ RKb3*a5[+bPb3] # { (C+ by WinChloe 3.32)}   Five times creation of white Sentinels antibatteries Pawn/LEO in five different directions. Five time a specific black Bristol RAO - Rose-Kangaroo with Sentinels mates after moves of the forward piece RK of the special battery. A circular geometry in the play of black thematic pieces that remind persecution or magnetism. Task in Meredith form. It's interesting that another version (with 4 solutions) is also possible: Through with "only" 4 solutions this version has also some aesthetical pluses - with some tries (or dual-avoidance nuances) by the formation of white anti-batteries. (Author)

### 21 Responses to No.900 (PAP)

1. seetharaman says:

It is a fantastic problem, the best I have seen using sentinels and probably one of the top problems in Juliafairies this year! The play of Nao and Rose-KA one after the other is complex and striking! A great tribute to the inventor of Sentinels. The master shows that the sentinel has so many secrets yet to be discovered, especially handled by such talented composers.

• Nikola Predrag says:

The problem is fantastic but the play of NAO has nothing to do with this.
BTW, the definition of RAO on this site is anything but clear:
RAO The Chinese Rose, moves like a Queen but on Rose-lines only.

“…like a Queen but…” what?-not like a Queen at all?

• seetharaman says:

You are right Nikola. I followed the solution correctly as RAO due to animation, but got confused while writing my comments! 🙁

2. seetharaman says:

I think it is Rose chinese at d2 … not Nao.

3. petko petkov says:

Thanks for your comments! Yes, of course on d2 stands a black RAO – this is my technical error admitted in writing of the text. I will send to Julia correction of the solution, also with some additions. By the by the problem was tested with the wonderful program of Christian Poisson Win Chloe – with version 3,32!

• Julia says:

Nikola, I know, the db of fairy definitions needs to be updated/corrected. I’m just out of time… Here I’ve added a better one for Rao (I believe).

4. Petko Petkov says:

Thank You very much, Julia!

5. Kjell Widlert says:

Wonderful events on the pseudo-circle b3-d2-f3-g5-f7-d8-b7-a5-b3: first the Rao moves clockwise over the Rose-Kangaroo to a suitable square, leaving a bPd2 behind; then the Rose-Kangaroo moves counter-clockwise over both the Rao and Pd2, leaving a mating Pb3 behind. I see the white Leo manoeuvres as a side motif, but they are an extremely efficient way of forcing the mating moves.

The one disadvantage is inherent in the matrix: the mates are not model, because both Rao and Rose-Kangaroo guard b3 at the end.
(In the composer’s version, the mates are pure because the Rao starts further away from the wK so only the Rao guards b2, but they are not economical as the Rose-Kangaroo is not participating in the mate.)
I don’t find this terribly important.

• Stephen Emmerson says:

I think both pieces move counter-clockwise – the RAO moves like a rose when not capturing, not a rose-lion, and Nikola’s correct that the bP is guarded twice from 3 directions in each version – maybe you started thinking of rosehopper?
“A rose by any other name would make ver different moves” – wasn’t it Shakespeare that said that?

6. Nikola Predrag says:

Kjell, either you treat the RAO as the Rose-Lion or I’m confused about RAO (and about Rose-KA too).
Both in the original and the version, I see RAO guarding the mating Pawn twice (from 2 directions) and Rose-Kangaroo once (via the switch-back route).
Probably I’m tired, I’ll try again tomorow 🙁

• Kjell Widlert says:

You’re right, Nikola. All this running around in circles must have made my head spin…
The Rao is a Chinese Rose, so it moves like a Rose when not capturing, so in B1 it actually moves counter-clockwise, just like the Rose-Kangaroo does in B2. And when capturing (and checking) it can move any distance beyond the hurdle, so it doesn’t matter if it starts close to the wK or further away from it – so both 900 and the version have double guards of the mating bP.
The events on the pseudo-circle are still wonderful!

• Nikola Predrag says:

Kjell, that little “spin” in the head is the basis of the human ability to create an abstraction. You have imagined a possible idea which doesn’t match exactly the properties of the two Rose-kinds present on the board.

If in the Petkov’s version, Rose-Kangaroo is replaced by Rose-hopper (on b2) and bRAO is on d1 (instead of f2), there would be some cook-solutions. They could be eliminated by removing bPd3 and adding wPe2, and there would be no solution at all.
But in each of the 4 “intended” lines of the play (W1,B1,W2 as in the version), Black would have the unique refutation 2…RAxLE, using Rose hopper as a hurdle.

However, your “delusive idea” was probably created by your good intuition, for instance:
h#2; Condition Sentinelles (RP is Rose-hopper)
1.LEe5[+wPf6] RAf7[+bPd2] 2.LEg5[+wPe5]+ RPxg5[+bPb3]#
1.LEc6[+wPf6] RAa5[+bPd2] 2.LEb7[+wPc6]+ RPxb7[+bPb3]#
1.LEd6[+wPf6] RAb7[+bPd2] 2.LEd8[+wPd6]+ RPxd8[+bPb3]#

Both bRA and bRP guard flights in the mates.

• Kjell Widlert says:

You read my mind like an open book 🙂 Yes, it was something like this I thought I was seeing.

7. Stephen Emmerson says:

A really good problem, and very accessible – whoever provides JF No.1000 has a hard task now.

8. shankar ram says:

A Great Memorial problem for Ananthanarayanan!
Exotic combination of hs#, Sentinels, Chinese Rose and Kangaroo(Aussie? ;-)) Rose line play. A geometry lesson seems in order…!

• seetharaman says:

hm.. Shankar has Good talent to shine as Professor !

9. petko petkov says:

Regarding my №900 Nichola Predrag publish the following version:
“…….However, your “delusive idea” was probably created by your good intuition, for instance ( on the occasion of Kjell Widlerts comment):
h#2; Condition Sentinelles (RP is Rose-hopper)
1.LEe5[+wPf6] RAf7[+bPd2] 2.LEg5[+wPe5]+ RPxg5[+bPb3]#
1.LEc6[+wPf6] RAa5[+bPd2] 2.LEb7[+wPc6]+ RPxb7[+bPb3]#
1.LEd6[+wPf6] RAb7[+bPd2] 2.LEd8[+wPd6]+ RPxd8[+bPb3]#
Both bRA and bRP guard flights in the mates”.

I once again thank Nicola`s and other commentators for the interest that they exhibit towards my problem!
But in my opinion, this version is unacceptable and I will point out many reasons for this.
1. Of course, this problem (here is used exactly the LEO-location&antibattery-creation from my version with 4 solutions) is with only 4 solutions but not by five, as is the original! It is a very essential minus of the proposed version because in four solutions the square “f3” remains unvisited – therefore – the paradoxical geometry of the original here is not preserved. (see the great scheme of Shankar!). In N900 in the process of play on each field by the large Rose-circle b3 – d2 – f3 – g5 – f7 – d8 – b7 – a5 there is white or black figure! By the by, in the course of my work I have presented many versions of this task with 4 solutions – including and those by using of Rose-hopper, by using of model-mates etc.
According to already mentioned reason – very significant in quantitative and qualitative terms, I chose the the version with 5 solutions!
2. For me, the main quality of a problem is the complex of ideas – This complex must be sufficiently interesting, complex and even paradoxical. It is not mandatory in every case and at all costs the play to ends with model mats – especially when the attainment of such finals obviously is not possible or leads to big compromises – for example – reducing the number of solutions -as in the version of Predrag, the use of the most powerful white figure – queen, just as technical and stationary element, etc. Incidentally,
I think that there is no matter the fact that in my №900 the square b3 is attacked twice. It is obvious that with 5 thematic solutions moldel mates are not possible here. The thematic black figures play with maximum activity, but will be fetched and unrealistic if we expect of them more “feats”!
Do not assume that I hate the model mats – the opposite is true : Nearly 1,000 of my composed problems (almost 16%) are created with model mats! I think that as a judge of competitions also I appreciate properly the tasks with model matеs
But I’ve never prepared to sacrifice an interesting idea, due to model mate – in particular – to shorten contents, to maim the wealth of ideas, only in the name of the “sacred model mate”! My principle is the following – model mate is an interesting and nice finish. It is good to achieve a model mate, if it is possible without compromises! But the model matе should be not a fanatical purpose!
3. I already mentioned that (on the occasion of Juraj Lorinc`s comment) that I appreciated as an aesthetical weakness the “dual routes” of the piece(s) Rose&Family , for exmple – such as in the Predrag`s version: RAg5 but via e4-g5 or f3-g5; RAf7 – but via c4 – d6-f7 or f3-g5-f7 etc.
A similar weakness (as an improvement) was proposed by our good friend Kenneth about my problem № 895 –Julias Fairies, 2015-09-16:
the proposal was: to remove black Sc2 and to add blacl Pc5 – without change of the solutions! BUT!!!! In such position is obviously that the initiall setting is not quite normal in aesthetical attitude: for example, here the square “f5” is already controlled from RAa3 (via Pe3) but the other thematic fields: “e4” and “f6” arw not controllwd in the beginning! This aesthetic disbalance – the unequal status of the three black themed pieces – disturbs from the outset! The same I have to repeat for mate-finals in solutions a) and b) – here the square f5 is controlled twice – with help of the black Pd6 and from white Pe3! So the the black mating Pawn on “d6” includes in a) and b) solutions only one black thematic piece but in solution c) – two thematic pieces!
In other words – the double control of RAa3 over “f5” violates also the thematic identity in the play of Pd6! This is a good example how a “small compromise” can lead to another, more unpleasant disadvantage!
Therefore in my №895 the black Sc2 is a very usefull piece!

10. Nikola Predrag says:

I didn’t publish “my version”, that is just an example of reciprocal hurdle-functions of 2 black thematic pieces which both have a guarding function in the mates.
That’s the idea which the example should just roughly illustrate, without any ambition of a “perfect” realization. There are no 4 model mates and I am not even motivated to care about the construction or some personal esthetic criteria, exactly because there is the published original and the original author’s version.
It was simply an illustrated discussion about the Kjell’s comment and the “inversion of directions”, nothing more.

11. Ganapathi says:

Shankar Ram’s prob. no. 1073 made me look up Petkov’s 900.
Tho’ Rao at d2 is mentioned below the problem, the piece is not found in the diag. If the correction is made in the diag. it will greatly help first-time viewers to follow the solution!

12. shankar ram says:

Strange…
It was there before…
Seems to have gone missing in between!

• Julia says:

Really strange.. Fixed!