1. there are 366 possible dates for a year
2. each could have significance for someone
3. filter these significances by something
- a large number of people who celebrate by having a day off work
- days with a special greeting
- days with a special meal (or abstinence)
- days that signify victory (or defeat)
- days that are not like most other days of the year
4. even with this trivial set there is a complexity problem
- every day is many people's birthday
- every weekend is a holiday
- each criterion requires an unspecified threshold
Happy New Year!