EntityQ467606· pop 38· linked from 657 articlesmodel theorySign in to savestudy of classes of mathematical structures from the perspective of mathematical logicConnectionsfirst-order logicEntityelementary equivalenceEntitysemantic theory of truthEntitymathematical logicEntityinjectionEntityformal languageEntitycardinal numberEntitycountable setEntitycontinuum hypothesisEntityformal systemEntityrecursive setEntityBoolean algebraEntityGödel's completeness theoremEntitysemantics of logicEntitystructureEntityultraproductEntityHoward Jerome KeislerEntitydescriptive complexity theoryEntityground expressionEntitydiagramEntityCategoriesMathematical logicMathematical proofsModel theory