EntityQ4155615· pop 7· linked from 35 articlesHilbert's twenty-first problemSign in to saveOn linear differential equations with certain propertiesConnectionsmonodromyEntityHilbert's problemsEntityregular singular pointEntityInternational Standard Book NumberEntityDavid HilbertEntityHenri PoincaréEntityBernhard RiemannEntitydigital object identifierEntityInternational Standard Serial NumberEntitybibcodeEntitysurjective functionEntitycomplex planeEntitycontinuum hypothesisEntityRiemann surfaceEntityPierre DeligneEntityQ22908627EntityRiemann sphereEntityfundamental groupEntityGeorge David BirkhoffEntitymathematical singularityEntityCategoriesAlgebraic curvesHilbert's problemsOrdinary differential equations