The A3H Theorem: An Exact Formula for Computing Calendar Months Between Two Dates

The A3H Theorem: An Exact Formula for Computing Calendar Months This repository presents the A3H Theorem, a mathematical formula for the exact computation of the number of calendar months between two dates. Unlike traditional methods based on approximate day counts (such as dividing the number of days by 30), the theorem provides an exact, deterministic, and calendar-based solution that eliminates rounding errors and inconsistencies. The theorem is applicable wherever the precise computation of elapsed calendar months is required. Typical applications include taxation, accounting, banking, finance, payroll management, human resources, labor administration, social security, pension systems, insurance, contract management, legal procedures, project management, subscription and billing systems, lease and loan management, healthcare administration, education, and any software or information system involving month-based periods, delays, deadlines, leave management, monthly salaries, employee seniority, absences, holidays, or recurring monthly calculations. The repository contains the complete research paper together with the LaTeX source files, ensuring transparency, reproducibility, and future development. The A3H Theorem provides a rigorous mathematical foundation for exact calendar-month computation and offers a reliable alternative to conventional approximation methods used in many practical applications.