surplussurplus variablesurprisingsurroundsurroundingsurveillancesurveysurvey planningsurveyingsurveying by correspondencesurveying by direct observationsurveying by interviewingsurveying by mailsurveying by registration of current eventssurveyorsurvival functionsuslin theoremsuspendsuspensionsuspension bridgesuspension pointswarfsweepsweeping methodswitchswitchingswitching circuitswitching rulessyllogismsyllogism by absurdsyllogism of whysylowsylow groupsylow subgroupsylow theoremsylvestersylvester criterionsylvester lawsymbolsymbol of a pseudodifferential operatorsymbolicsymbolic designationsymbolic formsymbolic formualsymbolic languagesymbolic logicsymboliclysymchronicsymmetricsymmetric about the origin