chess-The Oxford Companion to Chess - First Edition by David Hooper & Kenneth Whyld

96 DUAL AVOIDANCE
serious dual is .nc lhal by-passes the conposefs
central idea so that his Nork loses its pointl
generally, this would be n dualina nain lARrArroN
Lesser duah occur in sidc-variations or by.play In
a.omposingrcuRNLyan enlrytbatisfound tohave
a serious dual would usuallt be dnqualilied, shile a
lesser dual might be accepted. (See comnenh
Duals arc somctnncs provided intentionally, and
onc kind of problem is that showing progressive
duah . A composer might show. say, Iile varia
tionsi in the 6nt rhere are live possible ma rg
moves. and one at a time thesc are climinated so
thar in tIc Iast varlation ihere is only one mating
DUAL AVOIDANCE. ln the nain variations oI any
sou.d DrBEcr rrArE PRoELTMS duah are aloided
because a bla.k mole that pennits onc matc aitl
preventolhers Thetern dual aloidance is applied
onl! $hen fie main vanalions are linked by means
of rc.iprocal and parallcl rclalionships. For ex
ample nr a iwo-mover rHR r .RoBLEM (dncd
nale) Blact nay have rwo DETENCES of a like kind.
a and br to cacn whitcappcarsto hale twonadnS
moves A and B both of a similar kindr in lacl
delence b rllows nrte A and prevents nare B
whcrcas dciin.c a all.ws 6aie B nnd prevents
mate A. The mate in oDevariation G thc avoided
dual' in the other. Black\ t*o delences shonld
prevent the duals in a sidilar nanner. (The
parallch cannot b. defned prccisely.) For an
example see r^!^ rHIME. Dualavoidance mav also
be shown $ilh three ormore varialions (SeeLy.Lr.
Dualaroidan.c in Bro.K pRoBr..Ms aho consists
oi linked variations. mu.h in the samc man.er
A problen iron lhe BoNUs socNs MS. latc l:th
ccnturyi tne carlicst known example of dnal
aloidance. The key 1 RhgTsetsupablock. liBlack
moveshis knighr loNardWhilehisachoiceollNo
naies, Ra8 and Rg8. OrhcNisconlyonc ofthese
malcs h availablc. Dual avoidaDce is shown in six
variations loryhich rhe black mores day be paned
thus: Nil .nd Nb7. Nc8 and NeS- (e8 rnd Kc8.
DMl avoidan.c mayaho bc shoND in problems
other lhan dned nates.
DUBTNIN, PYOTR VASILYEVICH (1909 83).
Soviet platcr. Intcrnational Mlster (i950), Inter
nalional CorrespondeDce Cbess Crandnaster
(1962)- rade union oiiicial. Inoler the-boardplay
he .onrpctcd in lour USSR Championships with
modest results. his best place beine cqual sevenlh
in 1940r and he shared liBt prize in tbe RSFSR
(Rusian Federation) .h.npionship. 1949. Later
he took up posral.hc$, making his best achieve
ment when he came second to o'(ELLy nr lhc 3rd
Wortd Co.respondenc€ Cbanpionship, 1959 62.
DUBOIS, SERAFINO (l8l?-99). ltaly\ strongest
player in the l850saDd 1860s. I Ie mer lew masters
trom other coundes. ln 1845 rmrl, visning
Ronc, playcd many fiicndly eamcs sith Duboh,
who won about iwo-thi.ds oI themi in ?aris ten
years later he won about the sane proporlion of
sode l0 games played lgainst nMn8.. At rhe
I-ondon rournamcnt ol 1862 Duboh sharedlourh
place wilh G. A. M{DoNNLrLafter^NDrRssrN (the
winner), L. PAULSEN. and owEr_, bul wasarvarded
liith prize becalse he had Non more sames bl
dcfauli. Immcdiaicly drc tonrnamcnr cnded he
played and lost (+3=1 5) a nralch again$
sErNIrz. rinner oI the sixth prne Dubois was
probably not such a sfodg player as $e reo.d
suggcsts- for qhen he net wylill, Riliere, and
Stenri, none Nas vet 2t his full slrcngth In Apr.
1863 Dubois went irom Englaod ro Holland,
intending a longslal, bur not likine rhe climare he
rclurncd 10 Rome, the ctr ol his birrh. abour leo
yea6 laier. There he played to lhe ]talian lass,
Nbich pemnted &ee .^srxNc, as he prefered,
aod his inltue.ce nn] have delnled Iuly\ falling
inlo line Nilh thc castling law uscd chcwherc in
Europe. Belween 1868 aDd 1873 he wole a
lhree volune worL on tbe openings. giling vanaiions
with andvithour ltee caslling: rhis book Nas
soo! forgolten, but hh book oI lhc Romc tounranent.
1875, is oI some hislorical i.lerest: lhis
to m.nent was the 6rn held in Ilaly.
DUCIiAMP, MARCEL (1887 l!66), French
.he$ playcr and rc.own.d arlist. Acompetitorin
thc vo d anraleur championship oI 1924, tour
Fren.hchampionsbips lrom 1r,l lo 1928, and tbut
Ollmpiads Irom 1928 10 1913, l)uchamp aho
played in scvcral minor tournanrents, nolably
sharing 6Bt prize with BLBERSTADT and J. J.
OHanlon ilHyares 1928 with HalbcNtadt he
Ntorc L',Oppolitian el le! cases .oajugi$ eht
rl.onc,l,ier (1932)- publishcd in a limited edition ol
1.000 copies. His obsesion ior rhe g!Dc nrlcnsi6cd
ns be grew oldcr OI hk matriaec ir 1927 Man Ray
*ailes: Dmhamp spent most oI the one veek rhe!
liled together studying chess pioblens, and his
bride. in desper.te rediaion, gor uI onc night
when he wns asleen and glucd thc chcss pieces lo
rheboard.l hcywcrc divor.edthreenonthslater'
Duchanrp used chess themes in sever.l oi his
painrings aml collages. and is rbe nost highly
esleened .rtisl ro play che$ ,t mastcr lcvcl his