More static types using rector.

src/FactorGraphs/Factor.php

@@ -31,9 +31,9 @@ abstract class Factor implements \Stringable
     }
 
     /**
-     * @return mixed The log-normalization constant of that factor
+     * @return float The log-normalization constant of that factor
      */
-    public function getLogNormalization()
+    public function getLogNormalization(): float
     {
         return 0;
     }

src/FactorGraphs/FactorGraphLayer.php

@@ -21,7 +21,7 @@ abstract class FactorGraphLayer
     /**
      * @var array<int,array<int,object>>
      */
-    private $inputVariablesGroups = [];
+    private array $inputVariablesGroups = [];
 
     protected function __construct(private readonly TrueSkillFactorGraph $parentFactorGraph)
     {