Doomsday of a year
E637559
Doomsday of a year is a specific weekday that recurs on certain anchor dates throughout that year, enabling quick mental calculation of any date’s weekday.
All labels observed (2)
| Label | Occurrences |
|---|---|
| Doomsday (reference weekday for a year) | 1 |
| Doomsday of a year canonical | 1 |
How this entity was disambiguated
This entity first appeared as the object of triple T7030533 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.
NED1
Entity disambiguation (via context triple)
gpt-5-mini-2025-08-07
Target entity: Doomsday of a year Context triple: [Conway’s Doomsday algorithm, usesConcept, Doomsday of a year]
-
A.
Doomsday
"Doomsday" is a highly acclaimed 2006 Doctor Who television episode that concludes the battle between the Cybermen and the Daleks while marking the emotional farewell between the Tenth Doctor and Rose Tyler.
-
B.
Doomsday
Doomsday is a monstrous, nearly indestructible Kryptonian creature known in DC Comics for killing Superman and serving as one of his most powerful foes.
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C.
DOOMS
DOOMS is a supernatural condition in the Death Stranding universe that grants individuals heightened sensitivity to and interaction with the realm of the dead and its entities.
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D.
End of the World
"End of the World" is the 1968 debut studio album by Greek progressive rock band Aphrodite's Child, known for its psychedelic sound and melancholic title track.
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E.
Doom and Gloom
"Doom and Gloom" is a 2012 rock song by The Rolling Stones, released as one of the new tracks on their greatest hits compilation "GRRR!" and noted for its classic Stones sound and politically charged lyrics.
- F. None of above. chosen
- G. Unsure - the case is ambiguous/there is not enough information to decide.
NED2
Entity disambiguation (via description)
gpt-5-mini-2025-08-07
Target entity: Doomsday of a year Target entity description: Doomsday of a year is a specific weekday that recurs on certain anchor dates throughout that year, enabling quick mental calculation of any date’s weekday.
-
A.
Doomsday
"Doomsday" is a highly acclaimed 2006 Doctor Who television episode that concludes the battle between the Cybermen and the Daleks while marking the emotional farewell between the Tenth Doctor and Rose Tyler.
-
B.
Doomsday
Doomsday is a monstrous, nearly indestructible Kryptonian creature known in DC Comics for killing Superman and serving as one of his most powerful foes.
-
C.
DOOMS
DOOMS is a supernatural condition in the Death Stranding universe that grants individuals heightened sensitivity to and interaction with the realm of the dead and its entities.
-
D.
End of the World
"End of the World" is the 1968 debut studio album by Greek progressive rock band Aphrodite's Child, known for its psychedelic sound and melancholic title track.
-
E.
Doom and Gloom
"Doom and Gloom" is a 2012 rock song by The Rolling Stones, released as one of the new tracks on their greatest hits compilation "GRRR!" and noted for its classic Stones sound and politically charged lyrics.
- F. None of above. chosen
Statements (49)
| Predicate | Object |
|---|---|
| instanceOf |
calendar concept
ⓘ
computational calendar method ⓘ day-of-week rule ⓘ |
| appliesTo |
Gregorian calendar
NERFINISHED
ⓘ
Julian calendar NERFINISHED ⓘ |
| basedOn |
modular arithmetic
ⓘ
weekday cycles ⓘ |
| calculatedFrom |
century anchor day
ⓘ
leap year status ⓘ year's last two digits ⓘ |
| developedBy | John Horton Conway NERFINISHED ⓘ |
| hasAdvantage |
does not require written tables
ⓘ
enables fast mental weekday computation ⓘ requires only simple arithmetic ⓘ |
| hasAnchorDate |
April 4
ⓘ
August 8 ⓘ December 12 ⓘ February 28 in common years ⓘ February 29 in leap years ⓘ July 11 ⓘ June 6 ⓘ May 9 ⓘ November 7 ⓘ October 10 ⓘ September 5 ⓘ the last day of February ⓘ |
| hasDefinition | a specific weekday on which a set of anchor dates fall in a given year ⓘ |
| hasLimitation |
assumes use of a specific calendar system
ⓘ
differs between Gregorian and Julian calendars ⓘ |
| hasOutcome | a weekday index from 0 to 6 ⓘ |
| hasProperty |
can be any of the seven weekdays
ⓘ
depends on the year number ⓘ is constant within a given year ⓘ is the same weekday for all doomsday dates in that year ⓘ repeats every 400 years in the Gregorian calendar ⓘ |
| hasStep |
adjust for the year's last two digits
ⓘ
find the century anchor day ⓘ reduce result modulo 7 ⓘ |
| isComponentOf | calendar arithmetic ⓘ |
| isTaughtIn |
mental calculation courses
ⓘ
recreational mathematics ⓘ |
| partOf | Doomsday algorithm NERFINISHED ⓘ |
| relatedTo |
Doomsday rule
NERFINISHED
ⓘ
Zeller's congruence NERFINISHED ⓘ anchor day of a century ⓘ mental calculation techniques ⓘ perpetual calendar ⓘ |
| usedFor |
determining the weekday of any date in the same year
ⓘ
mental calculation of weekdays ⓘ |
How these facts were elicited
The pipeline generated the facts above by prompting gpt-5.1 with this entity's name + description and the instruction below.
Instruction
You are a knowledge base construction expert. Given a subject entity and a description of it, return factual statements that you know for the subject as a JSON list of dictionaries(triples), where keys must be "subject", "predicate" and "object". The number of facts may be very high, between 25 to 50 or more, for very popular subjects. For less popular subjects, the number of facts can be very low, like 5 or 10. # Requirements - If you don't know the subject at all, return an empty list. - If the subject is not a named entity, return an empty list. - Include at least one triple where predicate is "instanceOf". - Do not get too wordy. - Separate several objects into multiple triples with one object.
Input
Subject: Doomsday of a year Description of subject: Doomsday of a year is a specific weekday that recurs on certain anchor dates throughout that year, enabling quick mental calculation of any date’s weekday.
Referenced by (2)
Full triples — surface form annotated when it differs from this entity's canonical label.
this entity surface form:
Doomsday (reference weekday for a year)