proleptic Gregorian calendar
E389332
The proleptic Gregorian calendar is the extension of the modern Gregorian dating system backward in time to dates before its historical introduction in 1582.
All labels observed (1)
| Label | Occurrences |
|---|---|
| proleptic Gregorian calendar canonical | 1 |
How this entity was disambiguated
This entity first appeared as the object of triple T3787600 — 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: proleptic Gregorian calendar Context triple: [Common Era, isPartOf, proleptic Gregorian calendar]
-
A.
Julian calendar
The Julian calendar is an ancient solar calendar introduced by Julius Caesar in 45 BCE, historically used throughout Europe and still employed by some Eastern Christian churches for liturgical purposes.
-
B.
Revised Julian calendar
The Revised Julian calendar is a modernized version of the traditional Julian calendar, adopted by several Eastern Orthodox Churches to more closely align fixed feast dates with the Gregorian calendar while retaining the Orthodox Paschalion.
-
C.
Gregorian Code
The Gregorian Code was an early 5th-century compilation of Roman imperial laws that served as a key precursor to later codifications such as the Theodosian Code.
-
D.
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.
-
E.
Long Count calendar
The Long Count calendar is an ancient Mesoamerican timekeeping system, most notably used by the Maya, that tracks days in a linear count from a mythological starting point to record historical and cosmological events.
- 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: proleptic Gregorian calendar Target entity description: The proleptic Gregorian calendar is the extension of the modern Gregorian dating system backward in time to dates before its historical introduction in 1582.
-
A.
Julian calendar
The Julian calendar is an ancient solar calendar introduced by Julius Caesar in 45 BCE, historically used throughout Europe and still employed by some Eastern Christian churches for liturgical purposes.
-
B.
Revised Julian calendar
The Revised Julian calendar is a modernized version of the traditional Julian calendar, adopted by several Eastern Orthodox Churches to more closely align fixed feast dates with the Gregorian calendar while retaining the Orthodox Paschalion.
-
C.
Gregorian Code
The Gregorian Code was an early 5th-century compilation of Roman imperial laws that served as a key precursor to later codifications such as the Theodosian Code.
-
D.
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.
-
E.
Long Count calendar
The Long Count calendar is an ancient Mesoamerican timekeeping system, most notably used by the Maya, that tracks days in a linear count from a mythological starting point to record historical and cosmological events.
- F. None of above. chosen
Statements (46)
| Predicate | Object |
|---|---|
| instanceOf |
calendar system
ⓘ
extension of the Gregorian calendar ⓘ |
| appliesTo | years before 1 CE in astronomical year numbering ⓘ |
| assumes | continuous application of Gregorian rules to all years ⓘ |
| basedOn |
Gregorian calendar (Western churches)
ⓘ
surface form:
Gregorian calendar
|
| canBeCombinedWith | astronomical year numbering with year 0 ⓘ |
| category |
Calendars
ⓘ
Chronology ⓘ Time standards ⓘ |
| contrastsWith | proleptic Julian calendar ⓘ |
| differsFrom | historical calendars used before 1582 ⓘ |
| extendsTo | dates before 1582 ⓘ |
| hasAssumption |
Easter and movable feasts not historically aligned before 1582
ⓘ
no skipped days before 1582 ⓘ |
| hasEpochRelation | can be mapped to Julian day numbers ⓘ |
| hasProperty |
repeating 400-year cycle of dates
ⓘ
same weekday pattern as Gregorian calendar ⓘ |
| ignores |
historical calendar reforms before 1582
ⓘ
local adoption dates of the Gregorian calendar ⓘ |
| relatedTo |
Gregorian reform of 1582
ⓘ
surface form:
Council of Trent calendar reform
Gregorian reform of 1582 ⓘ |
| standardizedIn | ISO 8601 ⓘ |
| startDateConvention | no universally agreed earliest date ⓘ |
| usedBy |
ISO 8601
ⓘ
surface form:
ISO week date system
Java time API ⓘ PostgreSQL ⓘ
surface form:
PostgreSQL date types
Python datetime module ⓘ RFC 3339 date-time format ⓘ many database systems ⓘ |
| usedFor |
backward-compatible date calculations
ⓘ
conversion between historical and modern dates ⓘ uniform date arithmetic across historical periods ⓘ |
| usedIn |
ISO 8601 date representations
ⓘ
astronomy ⓘ chronology ⓘ computer date and time libraries ⓘ genealogy software ⓘ historical date conversion ⓘ historical research software ⓘ scientific datasets spanning long time ranges ⓘ |
| usesLeapYearRule |
Gregorian leap year rule
ⓘ
century years must be divisible by 400 to be leap years ⓘ divisible by 4 is leap year ⓘ |
| usesYearNumbering |
Common Era
ⓘ
surface form:
Anno Domini
Common Era ⓘ |
| usesYearZero | no year 0 in traditional AD numbering ⓘ |
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: proleptic Gregorian calendar Description of subject: The proleptic Gregorian calendar is the extension of the modern Gregorian dating system backward in time to dates before its historical introduction in 1582.
Referenced by (1)
Full triples — surface form annotated when it differs from this entity's canonical label.