Merge pull request #69 from pie-framework/feat/PD-4890

feat: fallback to numeric comparison for symbolic exponents in equations comparison, added test cases PD-4890

Author: CarlaCostea

src/fixtures/latex-equal/symbolic/exponentials-PD-4649.ts

@@ -0,0 +1,59 @@
+export default {
+  mode: "symbolic",
+  tests: [
+    // Cases where symbolic validation failed before
+
+    {
+      target: "B=500(\\frac{3}{4})^n",
+      ne: ["B=500(\\frac{1}{4})^{n-1}"],
+    },
+    {
+      target: "y=500(\\frac{3}{4})^n",
+      ne: ["y=500(\\frac{1}{4})^{n-1}"],
+    },
+    {
+      target: "a=500(\\frac{3}{4})^d",
+      ne: ["a=(\\frac{1}{4})^{d-1}"],
+    },
+    {
+      target: "b=500(\\frac{3}{4})^d",
+      ne: ["b=(\\frac{1}{4})^{d-1}"],
+    },
+    {
+      target: "f=4^g",
+      ne: ["f=4^{g-1}"],
+    },
+    {
+      target: "h=4^g",
+      ne: ["h=4^{g-1}"],
+    },
+
+    // Control test — should NOT be equal when using multiplication instead of exponentiation
+    {
+      target: "a=4*g",
+      ne: ["a=4*(g-1)"],
+    },
+
+    // Valid symbolic equivalence (should return true)
+    {
+      target: "x=3^n",
+      eq: ["x=3^n"],
+    },
+    {
+      target: "z=2^y",
+      eq: ["z=2^y"],
+    },
+    {
+      target: "v=(\\frac{5}{2})^x",
+      eq: ["v=(\\frac{5}{2})^x"],
+    },
+    {
+      target: "m=(\\frac{3}{4})^a",
+      eq: ["m=(\\frac{3}{4})^a"],
+    },
+    {
+      target: "k=(1.5)^p",
+      eq: ["k=(1.5)^p"],
+    },
+  ],
+};

src/fixtures/latex-equal/symbolic/exponentials-PD-4896.ts

@@ -0,0 +1,132 @@
+export default {
+  mode: "symbolic",
+  tests: [
+     {
+      target: "\\left(\\frac{1}{2}\\right)^n",
+      eq: ["\\left(\\frac{10}{20}\\right)^n"],
+    },
+    {
+      target: "\\left(\\frac{1}{2}\\right)^n",
+      eq: ["\\left(0.5\\right)^n"],
+    },
+    {
+      target: "\\left(\\frac{1}{2}\\right)^n",
+      eq: ["\\left(\\frac{2}{4}\\right)^n"],
+    },
+    {
+      target: "\\left(\\frac{10}{20}\\right)^n",
+      eq: ["\\left(\\frac{1}{2}\\right)^n"],
+    },
+    {
+      target: "\\left(0.5\\right)^n",
+      eq: ["\\left(\\frac{1}{2}\\right)^n"],
+    },
+    {
+      target: "\\left(\\frac{3}{2}\\right)^a",
+      eq: ["\\left(\\frac{6}{4}\\right)^a"],
+    },
+    {
+      target: "\\left(\\frac{3}{2}\\right)^a",
+      eq: ["\\left(1.5\\right)^a"],
+    },
+    {
+      target: "\\left(\\frac{1}{2}\\right)^n",
+      eq: ["\\left(1\\div2\\right)^n"],
+    },
+
+    // Division written with \left and \right — also should be equivalent
+
+    {
+      target: "\\left(1\\div2\\right)^n",
+      eq: ["\\left(10\\div20\\right)^n"],
+    },
+    {
+      target: "\\left(1\\div2\\right)^n",
+      eq: ["\\left(0.5\\right)^n"],
+    },
+    {
+      target: "\\left(1\\div2\\right)^n",
+      eq: ["\\left(2\\div4\\right)^n"],
+    },
+    {
+      target: "\\left(10\\div20\\right)^n",
+      eq: ["\\left(1\\div2\\right)^n"],
+    },
+    {
+      target: "\\left(0.5\\right)^n",
+      eq: ["\\left(1\\div2\\right)^n"],
+    },
+    {
+      target: "\\left(3\\div2\\right)^n",
+      eq: ["\\left(6\\div4\\right)^n"],
+    },
+    {
+      target: "\\left(3\\div2\\right)^n",
+      eq: ["\\left(1.5\\right)^n"],
+    },
+    // All of the following SHOULD be considered equivalent (eq)
+
+    {
+      target: "(\\frac{1}{2})^n",
+      eq: ["(\\frac{10}{20})^n"],
+    },
+    {
+      target: "(\\frac{1}{2})^n",
+      eq: ["(0.5)^n"],
+    },
+    {
+      target: "(\\frac{1}{2})^n",
+      eq: ["(\\frac{2}{4})^n"],
+    },
+    {
+      target: "(\\frac{10}{20})^n",
+      eq: ["(\\frac{1}{2})^n"],
+    },
+    {
+      target: "(0.5)^n",
+      eq: ["(\\frac{1}{2})^n"],
+    },
+    {
+      target: "(\\frac{3}{2})^a",
+      eq: ["(\\frac{6}{4})^a"],
+    },
+    {
+      target: "(\\frac{3}{2})^a",
+      eq: ["(1.5)^a"],
+    },
+    {
+      target: "(\\frac{1}{2})^n",
+      eq: ["(1\\div2)^n"],
+    },
+
+    // Control set – same expressions using division
+    {
+      target: "(1\\div2)^n",
+      eq: ["(10\\div20)^n"],
+    },
+    {
+      target: "(1\\div2)^n",
+      eq: ["(0.5)^n"],
+    },
+    {
+      target: "(1\\div2)^n",
+      eq: ["(2\\div4)^n"],
+    },
+    {
+      target: "(10\\div20)^n",
+      eq: ["(1\\div2)^n"],
+    },
+    {
+      target: "(0.5)^n",
+      eq: ["(1\\div2)^n"],
+    },
+    {
+      target: "(3\\div2)^n",
+      eq: ["(6\\div4)^n"],
+    },
+    {
+      target: "(3\\div2)^n",
+      eq: ["(1.5)^n"],
+    },
+  ],
+};

src/symbolic/compare-equations.ts

@@ -9,6 +9,8 @@ import {
   transformEqualityInExpression,
   expressionsCanBeCompared,
   solveQuadraticEquation,
+  hasSymbolicExponent,
+  areNumericallyEquivalent,
 } from "./utils";
 
 const m: any = mathjs;
@@ -49,6 +51,19 @@ export const compareEquations = (
     let firstEquationCoefficients: number[];
     let secondEquationCoefficients: number[];
 
+    if (
+      hasSymbolicExponent(firstExpression) ||
+      hasSymbolicExponent(secondExpression)
+    ) {
+      const isEquivalent = areNumericallyEquivalent(
+        firstExpression,
+        secondExpression,
+        firstEquationVariablesName
+      );
+     
+      return isEquivalent;
+    }
+
     if (firstEquationVariablesName.length === 1) {
       firstEquationCoefficients = getCoefficients(
         firstExpression,

src/symbolic/utils.ts

@@ -28,8 +28,8 @@ export const expressionsCanBeCompared = (
 
   firstEquation.traverse(function (node, path, parent) {
     if (node.isSymbolNode) {
-      firstSymbolNode = true
-      seriesNode = seriesNode || node.name.includes("[")
+      firstSymbolNode = true;
+      seriesNode = seriesNode || node.name.includes("[");
     }
     noFunctionOrArray =
       noFunctionOrArray || node.isFunctionNode || node.isArrayNode;
@@ -46,6 +46,49 @@ export const expressionsCanBeCompared = (
   return noFunctionOrArray && symbolNode && !seriesNode;
 };
 
+export const hasSymbolicExponent = (node: MathNode): boolean => {
+  let found = false;
+
+  node.traverse((n) => {
+    if (
+      n.isOperatorNode &&
+      n.op === "^" &&
+      !n.args[1]?.isConstantNode // Exponent is symbolic or compound
+    ) {
+      found = true;
+    }
+  });
+
+  return found;
+};
+
+export const areNumericallyEquivalent = (
+  exprA: MathNode,
+  exprB: MathNode,
+  variables: string[],
+  tolerance: number = 1e-10
+): boolean => {
+  const compiledA = m.compile(exprA.toString());
+  const compiledB = m.compile(exprB.toString());
+
+  const testValues = [1, 2, 3, 4, 5];
+
+  return testValues.every((val) => {
+    const scope = variables.reduce((acc, v) => {
+      acc[v] = val;
+      return acc;
+    }, {} as Record<string, number>);
+
+    try {
+      const resultA = compiledA.evaluate(scope);
+      const resultB = compiledB.evaluate(scope);
+      return Math.abs(resultA - resultB) < tolerance;
+    } catch {
+      return false;
+    }
+  });
+};
+
 // move the terms of the equations to the left hand side
 export const transformEqualityInExpression = (equality: MathNode) =>
   // remove added/subtracted numbers/variables from both sides of the equation