Implementation:Iamhankai Forest of Thought Check Expression

Knowledge Sources	Forest-of-Thought
Domains	Verification, Game_Solving
Last Updated	2026-02-14 03:00 GMT

Overview

Concrete tool for validating Game24 arithmetic expressions provided by the Forest-of-Thought repository.

Description

The check_expression function validates a candidate Game24 solution by: (1) extracting all digits from the expression, (2) verifying they match the input numbers using Counter-based multiset comparison, and (3) evaluating the expression to check it equals the target (24). Uses Python's eval() for expression evaluation with error handling for invalid expressions.

Usage

Called within forest_solve() and naive_solve() to validate candidate expressions before accepting them as solutions.

Code Reference

Source Location

• Repository: Forest-of-Thought
• File: methods/bfs.py
• Lines: L44-69

Signature

def check_expression(input_string, expression, target_result=24):
    """
    Validate arithmetic expression for Game24.

    Args:
        input_string (str): Available numbers (e.g., "1 2 3 4").
        expression (str): Candidate expression (e.g., "(1+2+3)*4").
        target_result (int): Target evaluation result (default: 24).

    Returns:
        bool: True if expression uses correct numbers and evaluates to target.
    """

Import

from methods.bfs import check_expression

I/O Contract

Inputs

Name	Type	Required	Description
input_string	str	Yes	Space-separated input numbers
expression	str	Yes	Candidate arithmetic expression
target_result	int	No	Target value (default: 24)

Outputs

Name	Type	Description
is_valid	bool	True if expression is valid

Usage Examples

from methods.bfs import check_expression

# Valid expression
assert check_expression("1 2 3 4", "(1+2+3)*4", 24) == True

# Wrong numbers
assert check_expression("1 2 3 4", "(1+2+5)*4", 24) == False

# Wrong result
assert check_expression("1 2 3 4", "1+2+3+4", 24) == False

Related Pages

Implements Principle

• Principle:Iamhankai_Forest_of_Thought_Expression_Validation

Requires Environment

• Environment:Iamhankai_Forest_of_Thought_OpenAI_API_Credentials