Zeller’s congruence
E637292
Zeller’s congruence is a mathematical formula used to determine the day of the week for any given date in the Gregorian or Julian calendar.
All labels observed (5)
| Label | Occurrences |
|---|---|
| Zeller’s congruence canonical | 2 |
| Gauss’s algorithm for the day of the week | 1 |
| Zeller's congruence | 1 |
| Zeller’s congruence for Gregorian calendar | 1 |
| Zeller’s congruence for Julian calendar | 1 |
How this entity was disambiguated
This entity first appeared as the object of triple T7030556 — 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: Zeller’s congruence Context triple: [Conway’s Doomsday algorithm, relatedTo, Zeller’s congruence]
-
A.
Conway’s Doomsday algorithm
Conway’s Doomsday algorithm is a mental calculation method devised by mathematician John Horton Conway for quickly determining the day of the week for any given date.
-
B.
Gregorian computus
Gregorian computus is the method used in the Gregorian calendar to calculate the date of Easter each year based on a refined solar and lunar cycle.
-
C.
The Calendar
"The Calendar" is a crime thriller play by Edgar Wallace that blends mystery and melodrama around horse racing and high society intrigue.
-
D.
proleptic Gregorian calendar
The proleptic Gregorian calendar is the extension of the modern Gregorian dating system backward in time to dates before its historical introduction in 1582.
-
E.
Coptic Epact Numbers
Coptic Epact Numbers is a Unicode block that encodes the historic numeral system used for writing numbers in the Coptic script.
- 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: Zeller’s congruence Target entity description: Zeller’s congruence is a mathematical formula used to determine the day of the week for any given date in the Gregorian or Julian calendar.
-
A.
Conway’s Doomsday algorithm
Conway’s Doomsday algorithm is a mental calculation method devised by mathematician John Horton Conway for quickly determining the day of the week for any given date.
-
B.
Gregorian computus
Gregorian computus is the method used in the Gregorian calendar to calculate the date of Easter each year based on a refined solar and lunar cycle.
-
C.
The Calendar
"The Calendar" is a crime thriller play by Edgar Wallace that blends mystery and melodrama around horse racing and high society intrigue.
-
D.
proleptic Gregorian calendar
The proleptic Gregorian calendar is the extension of the modern Gregorian dating system backward in time to dates before its historical introduction in 1582.
-
E.
Coptic Epact Numbers
Coptic Epact Numbers is a Unicode block that encodes the historic numeral system used for writing numbers in the Coptic script.
- F. None of above. chosen
Statements (44)
| Predicate | Object |
|---|---|
| instanceOf |
algorithm
ⓘ
calendar calculation method ⓘ mathematical formula ⓘ |
| appliesTo |
Gregorian calendar
ⓘ
linked to:
Gregorian calendar (Western churches)
Julian calendar ⓘ |
| assumes | months January and February treated as months 13 and 14 of previous year in common formulation ⓘ |
| canBeImplementedIn | any programming language supporting integer arithmetic ⓘ |
| category |
congruence formulas
ⓘ
date and time algorithms ⓘ |
| computes | weekday from a congruence modulo 7 ⓘ |
| dependsOn | encoding of weekday numbers ⓘ |
| describedAs | closed-form expression for weekday calculation ⓘ |
| field |
calendar computation
ⓘ
discrete mathematics ⓘ number theory ⓘ |
| hasComponent |
floor functions in some formulations
ⓘ
term depending on century ⓘ term depending on shifted month ⓘ term depending on year of century ⓘ term proportional to day of month ⓘ |
| hasConstraint |
requires correct handling of century transitions
ⓘ
requires correct mapping between numeric result and weekday names ⓘ |
| hasVariant |
Zeller’s congruence for Gregorian calendar
ⓘ
linked to:
Zeller’s congruence
Zeller’s congruence for Julian calendar ⓘ
linked to:
Zeller’s congruence
|
| input |
century
ⓘ
day of month ⓘ month ⓘ year ⓘ |
| isAlternativeTo | table-based weekday methods ⓘ |
| namedAfter | Christian Zeller ⓘ |
| output |
day of the week index
ⓘ
weekday name ⓘ |
| precision |
exact for valid Gregorian dates
ⓘ
exact for valid Julian dates ⓘ |
| relatedTo |
Doomsday rule
ⓘ
linked to:
Conway’s Doomsday algorithm
Gauss’s algorithm for the day of the week ⓘ
linked to:
Zeller’s congruence
Tomohiko Sakamoto’s algorithm ⓘ |
| requires | distinguishing between Gregorian and Julian calendar systems ⓘ |
| typicalDomain |
calendar software
ⓘ
computer date libraries ⓘ historical date analysis ⓘ |
| usedFor | determining the day of the week ⓘ |
| usesOperation |
integer division
ⓘ
modular arithmetic ⓘ |
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: Zeller’s congruence Description of subject: Zeller’s congruence is a mathematical formula used to determine the day of the week for any given date in the Gregorian or Julian calendar.
Referenced by (6)
Full triples — surface form annotated when it differs from this entity's canonical label.
linked to: Zeller’s congruence
linked to: Zeller’s congruence
linked to: Zeller’s congruence
linked to: Zeller’s congruence