WhenMathRecurrence Collision Finder
Enter two or more independent recurring schedules to find the dates where more than one of them actually lands. This expands each rule with the same shared recurrence engine used across WhenMath, so every rule is checked the same way.
Worked example
A weekly Monday standup and a monthly first Monday review, both starting on the same January Monday, land on that same date every time the monthly rule's first Monday happens to fall on a week the weekly rule also generates, which for a first Monday rule is every single time by definition. Change the monthly rule to the third Monday instead and the two schedules only coincide on whichever specific week of the month that happens to be the third Monday, a genuinely different and less frequent set of shared dates than the first-Monday version.
Common mistakes
- Assuming two weekly schedules on different weekdays can never collide. They still can if either rule's interval spans more than one week and the pattern eventually realigns.
- Checking too few occurrences per schedule to actually catch a collision that only happens several cycles in.
Limitations
This checks a bounded number of occurrences per schedule, not an infinite future, so a collision that only happens far beyond the checked window will not be reported.
Frequently asked questions
- Can I compare more than two schedules at once?
- Yes, add as many named schedules as needed, and any date matched by two or more of them is reported as a collision.
- What recurrence types are supported?
- The same shared set WhenMath's other recurrence engines use, including daily, weekly, monthly by day, and nth-weekday rules.