diff --git a/dist/constraint.d.ts b/dist/constraint.d.ts
index c1d5bd8..9658dee 100644
--- a/dist/constraint.d.ts
+++ b/dist/constraint.d.ts
@@ -12,8 +12,8 @@ import { Variable } from './variable.js';
  * @enum {Number}
  */
 export declare enum Operator {
-    Le = 0,
-    Ge = 1,
+    Le = 0,// <=
+    Ge = 1,// >=
     Eq = 2
 }
 /**
diff --git a/dist/constraint.d.ts.map b/dist/constraint.d.ts.map
index 7b000d9..cc27994 100644
--- a/dist/constraint.d.ts.map
+++ b/dist/constraint.d.ts.map
@@ -1 +1 @@
-{"version":3,"file":"constraint.d.ts","sourceRoot":"","sources":["../src/constraint.ts"],"names":[],"mappings":"AAAA,OAAO,EAAC,UAAU,EAAC,MAAM,iBAAiB,CAAA;AAE1C,OAAO,EAAC,QAAQ,EAAC,MAAM,eAAe,CAAA;AAEtC;;;;;;;;;;GAUG;AACH,oBAAY,QAAQ;IACnB,EAAE,IAAA;IACF,EAAE,IAAA;IACF,EAAE,IAAA;CACF;AAED;;;;;;;;;;;GAWG;AACH,qBAAa,UAAU;gBAErB,UAAU,EAAE,UAAU,GAAG,QAAQ,EACjC,QAAQ,EAAE,QAAQ,EAClB,GAAG,CAAC,EAAE,UAAU,GAAG,QAAQ,GAAG,MAAM,EACpC,QAAQ,GAAE,MAA0B;IAWrC;;;OAGG;IACI,EAAE,IAAI,MAAM;IAInB;;;;OAIG;IACI,UAAU,IAAI,UAAU;IAI/B;;;;OAIG;IACI,EAAE,IAAI,QAAQ;IAIrB;;;;OAIG;IACI,QAAQ,IAAI,MAAM;IAIlB,QAAQ,IAAI,MAAM;IAMzB,OAAO,CAAC,WAAW,CAAY;IAC/B,OAAO,CAAC,SAAS,CAAU;IAC3B,OAAO,CAAC,SAAS,CAAQ;IACzB,OAAO,CAAC,GAAG,CAAiB;CAC5B"}
\ No newline at end of file
+{"version":3,"file":"constraint.d.ts","sourceRoot":"","sources":["../src/constraint.ts"],"names":[],"mappings":"AAAA,OAAO,EAAC,UAAU,EAAC,MAAM,iBAAiB,CAAA;AAE1C,OAAO,EAAC,QAAQ,EAAC,MAAM,eAAe,CAAA;AAEtC;;;;;;;;;;GAUG;AACH,oBAAY,QAAQ;IACnB,EAAE,IAAA,CAAE,KAAK;IACT,EAAE,IAAA,CAAE,KAAK;IACT,EAAE,IAAA;CACF;AAED;;;;;;;;;;;GAWG;AACH,qBAAa,UAAU;gBAErB,UAAU,EAAE,UAAU,GAAG,QAAQ,EACjC,QAAQ,EAAE,QAAQ,EAClB,GAAG,CAAC,EAAE,UAAU,GAAG,QAAQ,GAAG,MAAM,EACpC,QAAQ,GAAE,MAA0B;IAWrC;;;OAGG;IACI,EAAE,IAAI,MAAM;IAInB;;;;OAIG;IACI,UAAU,IAAI,UAAU;IAI/B;;;;OAIG;IACI,EAAE,IAAI,QAAQ;IAIrB;;;;OAIG;IACI,QAAQ,IAAI,MAAM;IAIlB,QAAQ,IAAI,MAAM;IAMzB,OAAO,CAAC,WAAW,CAAY;IAC/B,OAAO,CAAC,SAAS,CAAU;IAC3B,OAAO,CAAC,SAAS,CAAQ;IACzB,OAAO,CAAC,GAAG,CAAiB;CAC5B"}
\ No newline at end of file
diff --git a/dist/maptype.d.ts b/dist/maptype.d.ts
index d1fef14..545716d 100644
--- a/dist/maptype.d.ts
+++ b/dist/maptype.d.ts
@@ -9,9 +9,9 @@ declare class IndexedMap<T extends {
     id(): number;
 }, U> {
     index: {
-        [id: number]: number;
+        [id: number]: number | undefined;
     };
-    array: Pair<T, U>[];
+    array: Array<Pair<T, U>>;
     /**
      * Returns the number of items in the array.
      */
diff --git a/dist/maptype.d.ts.map b/dist/maptype.d.ts.map
index a2aed70..88fdf9e 100644
--- a/dist/maptype.d.ts.map
+++ b/dist/maptype.d.ts.map
@@ -1 +1 @@
-{"version":3,"file":"maptype.d.ts","sourceRoot":"","sources":["../src/maptype.ts"],"names":[],"mappings":"AAAA,MAAM,WAAW,IAAI,CAAC,CAAC,SAAS;IAAC,EAAE,IAAI,MAAM,CAAA;CAAC,EAAE,CAAC,CAAE,SAAQ,UAAU,CAAC,CAAC,EAAE,CAAC,CAAC;CAAG;AAE9E,wBAAgB,SAAS,CAAC,CAAC,SAAS;IAAC,EAAE,IAAI,MAAM,CAAA;CAAC,EAAE,CAAC,KAAK,IAAI,CAAC,CAAC,EAAE,CAAC,CAAC,CAEnE;AAED,cAAM,UAAU,CAAC,CAAC,SAAS;IAAC,EAAE,IAAI,MAAM,CAAA;CAAC,EAAE,CAAC;IACpC,KAAK;;MAA2C;IAChD,KAAK,eAA0B;IAEtC;;OAEG;IACI,IAAI,IAAI,MAAM;IAIrB;;OAEG;IACI,KAAK,IAAI,OAAO;IAIvB;;;;OAIG;IACI,MAAM,CAAC,KAAK,EAAE,MAAM,GAAG,IAAI,CAAC,CAAC,EAAE,CAAC,CAAC;IAIxC;;;;OAIG;IACI,QAAQ,CAAC,GAAG,EAAE,CAAC;IAItB;;;;OAIG;IACI,IAAI,CAAC,GAAG,EAAE,CAAC;IAKlB;;;;;;;;OAQG;IACI,UAAU,CAAC,GAAG,EAAE,CAAC,EAAE,OAAO,EAAE,MAAM,CAAC,GAAG,IAAI,CAAC,CAAC,EAAE,CAAC,CAAC;IAYvD;;;;;;;OAOG;IACI,MAAM,CAAC,GAAG,EAAE,CAAC,EAAE,KAAK,EAAE,CAAC,GAAG,IAAI,CAAC,CAAC,EAAE,CAAC,CAAC;IAY3C;;;;OAIG;IACI,KAAK,CAAC,GAAG,EAAE,CAAC,GAAG,IAAI,CAAC,CAAC,EAAE,CAAC,CAAC;IAehC;;OAEG;IACI,IAAI,IAAI,UAAU,CAAC,CAAC,EAAE,CAAC,CAAC;CAS/B;AAED;;;GAGG;AAEH,cAAM,IAAI,CAAC,CAAC,EAAE,CAAC;IAQN,KAAK,EAAE,CAAC;IACR,MAAM,EAAE,CAAC;IARjB;;;;;OAKG;gBAEK,KAAK,EAAE,CAAC,EACR,MAAM,EAAE,CAAC;IAGjB;;OAEG;IACI,IAAI;CAGX"}
\ No newline at end of file
+{"version":3,"file":"maptype.d.ts","sourceRoot":"","sources":["../src/maptype.ts"],"names":[],"mappings":"AAAA,MAAM,WAAW,IAAI,CAAC,CAAC,SAAS;IAAC,EAAE,IAAI,MAAM,CAAA;CAAC,EAAE,CAAC,CAAE,SAAQ,UAAU,CAAC,CAAC,EAAE,CAAC,CAAC;CAAG;AAE9E,wBAAgB,SAAS,CAAC,CAAC,SAAS;IAAC,EAAE,IAAI,MAAM,CAAA;CAAC,EAAE,CAAC,KAAK,IAAI,CAAC,CAAC,EAAE,CAAC,CAAC,CAEnE;AAED,cAAM,UAAU,CAAC,CAAC,SAAS;IAAC,EAAE,IAAI,MAAM,CAAA;CAAC,EAAE,CAAC;IACpC,KAAK,EAAS;QAAC,CAAC,EAAE,EAAE,MAAM,GAAG,MAAM,GAAG,SAAS,CAAA;KAAC,CAAA;IAChD,KAAK,EAAS,KAAK,CAAC,IAAI,CAAC,CAAC,EAAE,CAAC,CAAC,CAAC,CAAA;IAEtC;;OAEG;IACI,IAAI,IAAI,MAAM;IAIrB;;OAEG;IACI,KAAK,IAAI,OAAO;IAIvB;;;;OAIG;IACI,MAAM,CAAC,KAAK,EAAE,MAAM,GAAG,IAAI,CAAC,CAAC,EAAE,CAAC,CAAC;IAIxC;;;;OAIG;IACI,QAAQ,CAAC,GAAG,EAAE,CAAC;IAItB;;;;OAIG;IACI,IAAI,CAAC,GAAG,EAAE,CAAC;IAKlB;;;;;;;;OAQG;IACI,UAAU,CAAC,GAAG,EAAE,CAAC,EAAE,OAAO,EAAE,MAAM,CAAC,GAAG,IAAI,CAAC,CAAC,EAAE,CAAC,CAAC;IAYvD;;;;;;;OAOG;IACI,MAAM,CAAC,GAAG,EAAE,CAAC,EAAE,KAAK,EAAE,CAAC,GAAG,IAAI,CAAC,CAAC,EAAE,CAAC,CAAC;IAY3C;;;;OAIG;IACI,KAAK,CAAC,GAAG,EAAE,CAAC,GAAG,IAAI,CAAC,CAAC,EAAE,CAAC,CAAC;IAehC;;OAEG;IACI,IAAI,IAAI,UAAU,CAAC,CAAC,EAAE,CAAC,CAAC;CAS/B;AAED;;;GAGG;AAEH,cAAM,IAAI,CAAC,CAAC,EAAE,CAAC;IAQN,KAAK,EAAE,CAAC;IACR,MAAM,EAAE,CAAC;IARjB;;;;;OAKG;gBAEK,KAAK,EAAE,CAAC,EACR,MAAM,EAAE,CAAC;IAGjB;;OAEG;IACI,IAAI;CAGX"}
\ No newline at end of file