diff --git a/core/invertGraph.ts b/core/invertGraph.ts
index 975a60c..5e9c223 100644
--- a/core/invertGraph.ts
+++ b/core/invertGraph.ts
@@ -1,6 +1,5 @@
-import { CategoryName } from './types/Category'
 import { Person, PersonList } from './types/Person'
-import mappings from './invertedMappings.json'
+import { Mapping, MAPPINGS } from './invertedMappings'
 
 export type InvertedPerson = {
   id: string
@@ -26,8 +25,7 @@ export function invertGraph(root: Person, list: InvertedPerson[]): PersonList {
   const personList: PersonList = { '0': root }
 
   for (const person of list) {
-    const degree = relationIdToDegree(person.relation)
-    const category = relationIdToCategory(person.relation)
+    const { category, degree } = relationIdToMapping(person.relation)
     const root = person.relatedTo === '' ? '0' : person.relatedTo
 
     personList[person.id] = {
@@ -52,20 +50,11 @@ export function invertGraph(root: Person, list: InvertedPerson[]): PersonList {
   return personList
 }
 
-function relationIdToDegree(relation: string): number {
-  const mapping = mappings[relation as keyof typeof mappings]
+function relationIdToMapping(relation: string): Mapping {
+  const mapping = MAPPINGS[relation]
   if (!mapping) {
     throw new Error('Unknown relation')
   }
 
-  return mapping.degree
-}
-
-function relationIdToCategory(relation: string): CategoryName {
-  const mapping = mappings[relation as keyof typeof mappings]
-  if (!mapping) {
-    throw new Error('Unknown relation')
-  }
-
-  return mapping.category as CategoryName
+  return mapping
 }
diff --git a/core/invertedMappings.json b/core/invertedMappings.json
deleted file mode 100644
index 695ec15..0000000
--- a/core/invertedMappings.json
+++ /dev/null
@@ -1,22 +0,0 @@
-{
-  "figlio": { "category": "children", "degree": 1 },
-  "nipote in linea retta": { "category": "children", "degree": 2 },
-  "pronipote in linea retta": { "category": "children", "degree": 3 },
-  "abnipote in linea retta": { "category": "children", "degree": 4 },
-  "genitore": { "category": "ascendants", "degree": 1 },
-  "fratello": { "category": "bilinear", "degree": 2 },
-  "nipote in linea collaterale": { "category": "children", "degree": 3 },
-  "pronipote in linea collaterale": { "category": "children", "degree": 4 },
-  "abnipote in linea collaterale": { "category": "children", "degree": 5 },
-  "zio": { "category": "others", "degree": 3 },
-  "cugino": { "category": "children", "degree": 4 },
-  "figlio di cugino": { "category": "children", "degree": 5 },
-  "nipote di cugino": { "category": "children", "degree": 6 },
-  "nonno": { "category": "ascendants", "degree": 2 },
-  "prozio": { "category": "others", "degree": 4 },
-  "secondo cugino": { "category": "children", "degree": 5 },
-  "figlio di secondo cugino": { "category": "children", "degree": 6 },
-  "bisavo": { "category": "ascendants", "degree": 3 },
-  "trisavo": { "category": "children", "degree": 4 },
-  "coniuge": { "category": "spouse", "degree": 1 }
-}
diff --git a/core/invertedMappings.ts b/core/invertedMappings.ts
new file mode 100644
index 0000000..6800d95
--- /dev/null
+++ b/core/invertedMappings.ts
@@ -0,0 +1,26 @@
+import { CategoryName } from './types/Category'
+
+export type Mapping = { category: CategoryName; degree: number }
+
+export const MAPPINGS: Record<string, Mapping> = {
+  figlio: { category: 'children', degree: 1 },
+  'nipote in linea retta': { category: 'children', degree: 2 },
+  'pronipote in linea retta': { category: 'children', degree: 3 },
+  'abnipote in linea retta': { category: 'children', degree: 4 },
+  genitore: { category: 'ascendants', degree: 1 },
+  fratello: { category: 'bilateral', degree: 2 },
+  'nipote in linea collaterale': { category: 'children', degree: 3 },
+  'pronipote in linea collaterale': { category: 'children', degree: 4 },
+  'abnipote in linea collaterale': { category: 'children', degree: 5 },
+  zio: { category: 'others', degree: 3 },
+  cugino: { category: 'children', degree: 4 },
+  'figlio di cugino': { category: 'children', degree: 5 },
+  'nipote di cugino': { category: 'children', degree: 6 },
+  nonno: { category: 'ascendants', degree: 2 },
+  prozio: { category: 'others', degree: 4 },
+  'secondo cugino': { category: 'children', degree: 5 },
+  'figlio di secondo cugino': { category: 'children', degree: 6 },
+  bisavo: { category: 'ascendants', degree: 3 },
+  trisavo: { category: 'children', degree: 4 },
+  coniuge: { category: 'spouse', degree: 1 },
+}
diff --git a/core/tests/invertedGraph.test.ts b/core/tests/invertedGraph.test.ts
index c855da9..feab8bc 100644
--- a/core/tests/invertedGraph.test.ts
+++ b/core/tests/invertedGraph.test.ts
@@ -58,10 +58,10 @@ test('siblings', () => {
 
   // prettier-ignore
   expect(graph).toStrictEqual({
-    '1': { id: list[0].id, name: list[0].name, available: list[0].available, degree: 2, category: 'bilinear', relatives: [], previous: '0' },
-    '2': { id: list[1].id, name: list[1].name, available: list[1].available, degree: 2, category: 'bilinear', relatives: [], previous: '0' },
-    '3': { id: list[2].id, name: list[2].name, available: list[2].available, degree: 2, category: 'bilinear', relatives: [], previous: '0' },
-    '4': { id: list[3].id, name: list[3].name, available: list[3].available, degree: 2, category: 'bilinear', relatives: [], previous: '0' },
+    '1': { id: list[0].id, name: list[0].name, available: list[0].available, degree: 2, category: 'bilateral', relatives: [], previous: '0' },
+    '2': { id: list[1].id, name: list[1].name, available: list[1].available, degree: 2, category: 'bilateral', relatives: [], previous: '0' },
+    '3': { id: list[2].id, name: list[2].name, available: list[2].available, degree: 2, category: 'bilateral', relatives: [], previous: '0' },
+    '4': { id: list[3].id, name: list[3].name, available: list[3].available, degree: 2, category: 'bilateral', relatives: [], previous: '0' },
     '0': { id: '0', name: 'Defunto', available: false, degree: 0, category: 'root', relatives: ['1', '2', '3', '4'], previous: null },
   })
 })