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coGecientsin
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cmsy10mr&(dimF')=2wewriteX$2 cmmi8r=mXrb(')forthevXarietryofrS-dimensionaltotallyisotropicsubspacesof'. FVoranryrS,+
thevXarietyXr }[issmoSothandpro jective.9Itisgeometricallyconnectedifandgonlygifr16=;(dimF')=2. Inparticular,3Xr Gisconnectedforanryrrifdim*'isoSdd.FVorevren-dimensional'andrǹ=V9(dimF')=2,RthevXarietryXr isconnectedifandonlythediscriminanrtof'isnon-trivial. IfthevXarietryXr
,eisnotconnected,ithastrwoconnectedcompSonenrtsandtheyareisomorphic.FInparticular,thedimensionofXr=