Add gUFO section of page for intervals of existence

examples/illustrations/existence_intervals/README.md

@@ -115,3 +115,105 @@ Some of the examples in the OWL-TIME specification include demonstrations of `ti
 * [5.4, "iCalendar"](https://www.w3.org/TR/owl-time/#iCal) instantiates the endurant "Abraham Lincoln" (node `_:TE-2`).
 * [5.6, "A Use Case for Scheduling"](https://www.w3.org/TR/owl-time/#scheduling) instantiates perdurants some teleconference and some meeting (nodes `ex:telecon` and `ex:meeting`, respectively).
 * [5.7, "Alignment of PROV-O with OWL-Time"](https://www.w3.org/TR/owl-time/#time-prov) states that `prov:Activity` and `prov:InstantaneousEvent` can be subclasses of `time:TemporalEntity` and `time:Instant`, respectively.
+
+
+## gUFO
+
+(gUFO version: [1.0.0](https://github.com/nemo-ufes/gufo/releases/tag/v1.0.0).)
+
+gUFO's topmost class that describes an object that exists in a period of time is "Concrete Individual" (`gufo:ConcreteIndividual`), defined as the disjoint union of "Endurants," "Events," and "Situations."
+
+* `gufo:Endurant` corresponds with UCO Issue 535's "Endurant".
+* `gufo:Event` corresponds with UCO Issue 535's "Perdurant".
+* `gufo:Situation` is mostly out of scope of this discussion, though the interested can review a footnote about temporary `@type` applicability[^1].
+
+Concrete individuals have first and last instants in which they exist.  These instants are represented as `time:Instant` objects or as datatype literals (typed `xsd:date` or `xsd:dateTimeStamp`---and, pertinent to UCO, not `xsd:dateTime`).  Two properties, "has begin point" and "has end point," assign the first and last instants that any concrete individual exists as objects.  The properties have range `time:Instant`, inheriting the vocabulary and entailing the structures of OWL-Time as described above.
+None of the three subclasses of `gufo:ConcreteIndividual` specialize restrictions on those existence-bounding properties.  Hence, without loss of generality, we can review a `gufo:Endurant` and see the same time-related applicability for `gufo:Event`.
+
+This is an endurant (more specifically, a `gufo:Object`) with literal-valued instants describing the creation and termination timestamps TS0 and TS1:
+
+```json
+[
+    {
+        "@id": "kb:Object-bee97e78-8e5e-4ffe-9c2b-28e960f84bbc",
+        "@type": "gufo:Object",
+        "rdfs:label": "T",
+        "rdfs:comment": "A thing with a time-bounded existence.",
+        "gufo:hasBeginPointInXSDDateTimeStamp": {
+            "@type": "xsd:dateTimeStamp",
+            "@value": "2020-01-02T03:04:05.6789Z"
+        },
+        "gufo:hasEndPointInXSDDateTimeStamp": {
+            "@type": "xsd:dateTimeStamp",
+            "@value": "2021-02-03T04:05:06.7890Z"
+        }
+    }
+]
+```
+
+The literal-valued timestamps can also use `gufo:hasBeginPointInXSDDate` when only `xsd:date` is to be used.
+
+This is the same endurant with reified instants housing the beginning and end:
+
+```json
+[
+    {
+        "@id": "kb:Object-bee97e78-8e5e-4ffe-9c2b-28e960f84bbc",
+        "@type": "gufo:Object",
+        "rdfs:label": "T",
+        "gufo:hasBeginPoint": {
+            "@id": "kb:Instant-1a250c7b-19c5-4ec4-bed2-d05c9d438e9d",
+            "@type": "time:Instant",
+            "rdfs:label": "T0",
+            "time:inXSDDateTimeStamp": {
+                "@type": "xsd:dateTimeStamp",
+                "@value": "2020-01-02T03:04:05.6789Z"
+            }
+        },
+        "gufo:hasEndPoint": {
+            "@id": "kb:Instant-bbd8741a-4af8-4358-802b-a6fb8a4cf7dc",
+            "@type": "time:Instant",
+            "rdfs:label": "T1",
+            "time:inXSDDateTimeStamp": {
+                "@type": "xsd:dateTimeStamp",
+                "@value": "2021-02-03T04:05:06.7890Z"
+            }
+        }
+    }
+]
+```
+
+Intervals of existence do not appear to be defined directly in gUFO.  Also, since only the first and last instant of a concrete individual are specified, it is also not explicit in gUFO whether an individual's interval of existence needs to be continuous.  For instance, a `gufo:Situation` may be seen to hold for a period of time, such as a person temporarily being a student in a `gufo:TemporaryInstantiationSituation`[^1], then not hold (e.g., when the person graduates from a school), then hold again (e.g., when the person later enrolls in another school).
+
+Timestamps are constrained to `xsd:dateTimeStamp`, not `xsd:dateTime`, which is consistent with OWL-Time's deprecation of `time:inXSDDateTime`.  For UCO, this would necessitate transcoding `xsd:dateTime` timestamps with a non-OWL, and likely non-SPARQL, mechanism.
+
+The following figure shows the time coverage for `gufo:ConcreteIndividual`, re-using covering vocabulary from OWL-Time above:
+
+![Abstraction - gUFO Concrete Individual](figures/abstraction_gufo.svg)
+
+The mapping for `gufo:ConcreteIndividual` would be as follows:
+
+| Example class or triple | Corresponding class or triple |
+| --- | --- |
+| `ex:TimeBoundedThing` | `gufo:ConcreteIndividual` |
+| `ex:ExistenceInterval` | N/A |
+| `ex:Instant` | `time:Instant` |
+| `kb:T ex:hasExistenceInterval kb:E` | N/A |
+| `kb:T ex:existsAtAndSince kb:T0` | `gufo:hasBeginPoint` |
+| `kb:T ex:existsUntil kb:T1` | `gufo:hasEndPoint` |
+| `kb:T ex:hasCreationTimestamp "2020-..."^^xsd:dateTime` | `kb:t gufo:hasBeginPointInXSDDateTimeStamp "2020-..."^^xsd:dateTimeStamp` |
+| `kb:T ex:hasTerminationTimestamp "2021-..."^^xsd:dateTime` | `kb:t gufo:hasEndPointInXSDDateTimeStamp "2021-..."^^xsd:dateTimeStamp` |
+| `kb:E ex:hasStart kb:T0` | N/A |
+| `kb:E ex:hasEnd kb:T1` | N/A |
+| `kb:E ex:hasBeginningTimestamp "2020-..."^^xsd:dateTime` | N/A |
+| `kb:E ex:hasEndingTimestamp "2021-..."^^xsd:dateTime` | N/A |
+| `kb:T0 ex:hasTimestamp "2020-..."^^xsd:dateTime` | `kb:T0 time:inXSDDateTimeStamp "2020-..."^^xsd:dateTimeStamp` |
+| `kb:T1 ex:hasTimestamp "2021-..."^^xsd:dateTime` | `kb:T1 time:inXSDDateTimeStamp "2021-..."^^xsd:dateTimeStamp` |
+
+_Aside_: A side-by-side view of the gUFO and OWL-Time coverage show that an ontology importing gUFO and OWL-Time has complete coverage of the existence-intervals concepts suggested on this page.
+
+| OWL-Time | gUFO |
+| --- | --- |
+| ![Abstraction - OWL-Time Temporal Entity](figures/abstraction_time.svg) | ![Abstraction - gUFO Concrete Individual](figures/abstraction_gufo.svg) |
+
+[^1]: gUFO represents instantations that are not always true with `gufo:TemporaryInstantiationSituation`.  In the case where a person is temporarily a student, "student" is taken to be some subclass of "person" - e.g., `ex:Student rdfs:subClassOf ex:Person`.  For some time, it holds that `kb:person-3393... a ex:Student`, but this is not always true.  To hold this situationally-true statement in a knowledge graph, a `gufo:TemporaryInstantiationSituation` is included to note the conditions when `kb:person-3393...` is a `ex:Student`, instead of encoding the unqualified triple `kb:person-3393... a ex:Student`.  See `kb:TemporaryInstantiationSituation-da1aa582-1358-49bb-b058-4c33990fb9e8` in [`existence_intervals.json`](existence_intervals.json) for a demonstration of this representation.

examples/illustrations/existence_intervals/existence_intervals.json

@@ -76,6 +76,26 @@
             "rdfs:comment": "The instant that is the end of E.",
             "rdfs:label": "T1"
         },
+        {
+            "@id": "ex:Person",
+            "@type": [
+                "owl:Class",
+                "gufo:Kind"
+            ],
+            "rdfs:subClassOf": {
+                "@id": "gufo:Object"
+            }
+        },
+        {
+            "@id": "ex:Student",
+            "@type": [
+                "owl:Class",
+                "gufo:Role"
+            ],
+            "rdfs:subClassOf": {
+                "@id": "ex:Person"
+            }
+        },
         {
             "@id": "kb:ExistenceInterval-27802c47-1c75-43fa-ab4b-fc01aa6c2c92",
             "@type": "time:Interval",
@@ -108,6 +128,44 @@
                 "@value": "2020-01-02T03:04:05.6789Z"
             }
         },
+        {
+            "@id": "kb:Object-bee97e78-8e5e-4ffe-9c2b-28e960f84bbc",
+            "@type": "gufo:Object",
+            "gufo:hasBeginPointInXSDDateTimeStamp": {
+                "@type": "xsd:dateTimeStamp",
+                "@value": "2020-01-02T03:04:05.6789Z"
+            },
+            "gufo:hasEndPointInXSDDateTimeStamp": {
+                "@type": "xsd:dateTimeStamp",
+                "@value": "2021-02-03T04:05:06.7890Z"
+            },
+            "rdfs:comment": "A thing with a time-bounded existence.",
+            "rdfs:label": "T"
+        },
+        {
+            "@id": "kb:Person-3393dfc0-c765-4710-86db-8182c34de806",
+            "@type": "ex:Person",
+            "gufo:standsInQualifiedInstantiation": {
+                "@id": "kb:TemporaryInstantiationSituation-da1aa582-1358-49bb-b058-4c33990fb9e8"
+            },
+            "rdfs:label": "J. Doe"
+        },
+        {
+            "@id": "kb:TemporaryInstantiationSituation-da1aa582-1358-49bb-b058-4c33990fb9e8",
+            "@type": "gufo:TemporaryInstantiationSituation",
+            "gufo:concernsNonRigidType": {
+                "@id": "ex:Student"
+            },
+            "gufo:hasBeginPointInXSDDateTimeStamp": {
+                "@type": "xsd:dateTimeStamp",
+                "@value": "2018-09-01T00:00Z"
+            },
+            "gufo:hasEndPointInXSDDateTimeStamp": {
+                "@type": "xsd:dateTimeStamp",
+                "@value": "2022-06-16T00:00:00Z"
+            },
+            "rdfs:comment": "This is the situation where J. Doe is a student, which started to hold Sep 1 2018, and no longer held on Jun 16, 2022."
+        },
         {
             "@id": "kb:TimeBoundThing-b1fd892f-f190-4e15-a928-6c949867c59d",
             "@type": "owl:Thing",

examples/illustrations/existence_intervals/figures/Makefile

@@ -20,6 +20,7 @@ top_srcdir := $(shell cd ../../../.. ; pwd)
 
 all: \
   abstraction_all.svg \
+  abstraction_gufo.svg \
   abstraction_time.svg \
   abstraction_uco_1_3_0_action.svg \
   abstraction_uco_1_3_0_event.svg \

examples/illustrations/existence_intervals/figures/abstraction_gufo.dot

@@ -0,0 +1,25 @@
+digraph "abstraction" {
+	n_t [label="T (object):\nA gufo:ConcreteIndividual." color=blue fontcolor=blue] ;
+
+	n_e [label="E (object):\nThe existence interval of T." color=silver fontcolor=silver] ;
+
+	n_t0 [label="T0 (object):\nThe instant that is the beginning of E.\ntime:Instant" color=blue fontcolor=blue];
+	n_t1 [label="T1 (object):\nThe instant that is the end of E.\ntime:Instant" color=blue fontcolor=blue];
+
+	l_ts0 [label="ts0 (literal):\n2020-01-02T03:04:05.6789Z\nxsd:dateTimeStamp" shape="box" color=blue fontcolor=blue];
+	l_ts1 [label="ts1 (literal):\n2021-02-03T04:05:06.7890Z\nxsd:dateTimeStamp" shape="box" color=blue fontcolor=blue];
+
+	n_t -> n_e [label="T hasExistenceInterval E" color=silver fontcolor=silver] ;
+	n_t -> n_t0 [label="T existsAtAndSince T0\ngufo:hasBeginPoint" color=blue fontcolor=blue] ;
+	n_t -> n_t1 [label="T existsUntil T1\ngufo:hasEndPoint" color=blue fontcolor=blue] ;
+	n_t -> l_ts0 [label="T hasCreationTimestamp ts0\ngufo:hasBeginPointInXSDDateTimeStamp" color=blue fontcolor=blue];
+	n_t -> l_ts1 [label="T hasTerminationTimestamp ts1\ngufo:hasEndPointInXSDDateTimeStamp" color=blue fontcolor=blue];
+
+	n_e -> n_t0 [label="E hasStart T0" color=silver fontcolor=silver];
+	n_e -> n_t1 [label="E hasEnd T1" color=silver fontcolor=silver];
+	n_e -> l_ts0 [label="E hasBeginningTimestamp ts0" color=silver fontcolor=silver] ;
+	n_e -> l_ts1 [label="E hasEndingTimestamp ts1" color=silver fontcolor=silver] ;
+
+	n_t0 -> l_ts0 [label="T0 hasTimestamp ts0\ntime:inXSDDateTimeStamp" color=blue fontcolor=blue];
+	n_t1 -> l_ts1 [label="T1 hasTimestamp ts1\ntime:inXSDDateTimeStamp" color=blue fontcolor=blue];
+}