A Tour of the ORM Modeler POC

Getting Started

To use the tool yourself, you will need to login using Google Authentication. If you do this, your email address will be shared but no other information will be requested or stored.

Once logged in, click on New Model, provide a unique model name, click Ok and a blank canvas will be presented (as shown below).

User Interface Overview

Across the top left are the New Model button, Model selection dropdown, Export button, Import button, Rename Model button, Delete Model button and a Print model button.

Across the top right are the Connect Models menu (used to connect entity types and fact types across multiple canvases), Generate menu (used to generate the Semantic Model, Verbalizations, Narrative and a preview natural language to ORM feature), the Publish menu, a help button and an an application wide settings button.

On the left side, are the ORM ELEMENTS and MODEL EXPLORER panels. On the right side, are the Model Settings/Properties Panel and a multi-tab panel to display the Verbalizations, Model Narrative, the Semantic Model and the Model JSON (which is the full representation of the model in json).

At the bottom center is the Validation Results panel which displays modeling issues.

The left, right and bottom center panels can all slide left and right or up and down to make more room for the canvas. The React Flow diagram, embedded in the bottom-right of the canvas, can be temporarily removed using the control button at the bottom-left. These controls also provide zoom in/out, center canvas, lock canvas, and center diagram functions. Zooming the canvas in and out can also be done using the mouse.

Beginning Your Model

To begin modeling, the user will drag an Entity Type from the ORM ELEMENTS panel onto the canvas and then typically at least one other Entity Type or Value Type. These will be connected using a Fact Type, which is often a Binary Fact Type.

In the screenshot below, an Entity Type was dragged onto the canvas, its default name was selected, and then changed to 'Person'.

A Reference Mode (which defines how the entity type is identified) is then clicked, presenting the reference mode dropdown. Either one of the built-in reference modes can be selected or one may be manually entered. Note: Reference Modes are not mandatory but if one is not selected for an Entity Type then an External Uniqueness constraint is required to provide an identity for the Entity Type. This will be shown later in this tour.

Connecting Fact Types and Constraints

Once an Entity Type and another Entity or Value Type are placed on the canvas, a Fact Type (in this example, a Binary Fact Type) is dragged onto the canvas. To connect a Fact Type to an Entity Type or Value Type, select the center grab handle of the Entity or Value Type and drag the connection line to the grab handle on the target role. This connection can also be made in the opposite direction.

All fact types, except unary, must have an Internal Uniqueness Constraint (a rule that specifies which combination of roles in a fact type must be unique for each fact instance, ensuring there are no duplicate facts with the same participating objects). To add an Internal Uniqueness Constraint, right-click the target role to open a context menu, then select 'Add Uniqueness Constraint'. To apply the constraint across multiple roles, Shift-click to select them, then right-click to access the context menu and select 'Add Uniqueness Constraint'. The role or roles with the Internal Uniqueness Constraint will have a line above them to visually indicate the constraint. Note: Roles can also be added or deleted using this context menu. However, unary, binary, and ternary Fact Types are already pre-defined.

Note: The grab handles at the top and bottom of the Entity Type are used for Subtype/Supertype (i.e. is a) relationships which will shown later in this tour.

Role Properties and Fact Type Objectification

A role may also be mandatory (indicated by the solid black dot and M on the role box). The combination of the uniqueness constraint and mandatory constraint signifies an "exactly once" relationship (e.g., A Person is known by exactly one Name). The predicate phrase, such as "is known by," is edited via the Reading Text field in the properties panel. In this example, with "is known by," the Fact Type Name automatically becomes "Person is known by Name." This Fact Type Name can be manually overridden.

A Fact Type can also be objectified by checking 'Objectify Fact Type'. This transforms the Fact Type into an Entity Type, meaning a Reference Mode and Data Type will also apply to the Objectified Fact Type.

The data type of a RefMode or Value Type can be modified in the Properties Pane. Available data types include Text, Integer, Decimal, Real, Currency, Boolean, Date, DateTime and Media. Custom data types are not yet supported.

Objectified Fact Type in Action

This image shows an Objectified Fact Type. The Entity Type 'PersonName' is identified by an Integer ID. The grab handle at the top enables the Objectified Fact Type to participate in a role within another Fact Type.

Subtypes and Different Fact Types

In the example below, 'Student' is a subtype of 'Person' and inherits the identity of its supertype, 'Person' (which, in this case, is the Reference Mode, but could also be an External Uniqueness Constraint).

'hasLibraryAccess' is a unary fact type, meaning 'Student hasLibraryAccess' can be true, false, or, in an Open World model, unknown.

The example below illustrates a Ternary Fact Type: 'Student takes Course during Semester'.

External Uniqueness Constraint

This page introduces the External Uniqueness Constraint, which ensures that the combination of roles across multiple fact types uniquely identifies an entity. In this example, a Person is uniquely identified by FirstName, LastName, DateOfBirth and PlaceOfBirth (this is for illustrative purposes only as this is a strong assumption).

Exclusion Constraint

This section introduces the Exclusion Constraint, which indicates that two facts cannot both be true at the same time for the same entities. For example, a graduate student cannot both write and grade the same paper. Multiple sequences of multiple roles can be added to the diagram using the Sequence Editor menu, shown at the top left of the canvas.

Subset Constraint

This section demonstrates a Subset Constraint, which requires that one set of facts must be a subset of another. For example, if a GradStudent is a TA for a Course, they must also be taking that Course.

Subset, Exclusion, and Equality (not shown in this POC tour) constraints all support sequences of one or more roles.

Ring Constraint

Additionally, a Ring Constraint is shown. This constraint applies to relationships where an entity relates to another entity of the same type, like 'GradStudent advises GradStudent', and defines properties such as reflexivity or transitivity within that relationship.

This Ring Constraint specifies that the relationship "GradStudent advises GradStudent" is irreflexive (no student can advise themselves), asymmetric (if one student advises another, the reverse is not possible), and strongly intransitive (if one student advises a second, and the second advises a third, the first cannot advise the third, directly or indirectly).

Subtype Constraint

Finally, an Exclusive-Or Subtype Constraint is illustrated here, which defines how a supertype (e.g., Student) can be exclusively partitioned into multiple subtypes (e.g., GradStudent, UnderGradStudent). Rather than use connection lines for subtype constraints, this ORM Modeler identifies the supertype and subtypes using labels on the constraint element.

Complete Example Model

A screenshot of the complete model is provided below, and further down the page are the LLM-generated Model Verbalization and Model Narrative. These LLM outputs were not manually edited.

Model Verbalization

Each Person is identified by a Person ID.

Each Student is identified by a Student ID.

Each Course is identified by a Course Code.

Each Semester is identified by a Semester Name.

Each GradStudent is identified by a GradStudent ID.

Each Paper is identified by a Paper Name.

Each UnderGradStudent is identified by an UnderGradStudent ID.

FirstName is a kind of Text.

LastName is a kind of Text.

DateOfBirth is a kind of Date.

PlaceOfBirth is a kind of Text.

Each Person must have exactly one FirstName.

A Student may haveLibraryAccess.

Each [Student, Course, Semester] combination may appear only once.

Each Person must have exactly one LastName.

Each Person must have been born on exactly one DateOfBirth.

Each Person must have been born in exactly one PlaceOfBirth.

Each [GradStudent, Paper] combination may appear only once.

Each [GradStudent, Paper] combination may appear only once.

Each [GradStudent, Course] combination may appear only once.

Each [GradStudent, GradStudent] combination may appear only once.

Each Person is identified by FirstName, LastName, DateOfBirth, and PlaceOfBirth.

It is prohibited that a GradStudent grades a Paper and that same GradStudent writes that same Paper.

If a GradStudent is TA for a Course, then that GradStudent must take that Course.

No GradStudent advises that same GradStudent.

If a GradStudent advises a second GradStudent, then that second GradStudent does not advise the first GradStudent.

If a GradStudent advises a third GradStudent, then that third GradStudent does not advise the first GradStudent (indirectly or directly).

Every Student must be either a GradStudent or an UnderGradStudent, but not both.

Natural Language Interpretation of ORM Model

1. Model Overview

• Model Name: DemoModel
• Description: No specific description provided in the model.
• Constraint Interpretation Mode: Alethic
• World Assumption Mode: CWA

This model describes concepts and relationships within a university or educational domain, focusing on people, students, courses, and papers. It defines how different types of entities are identified and how they relate to each other through various facts and rules.

In Alethic mode, constraints are interpreted as statements of what *must be true* about the domain. Any data that violates a constraint is considered factually impossible or incorrect. For example, if a rule states 'A Person has exactly one Date of Birth', it means it is impossible for a person to have no date of birth or multiple dates of birth.

In CWA mode, the model assumes that anything not explicitly stated as true is considered false. This means if a fact is not recorded, it is assumed not to exist. For example, if a student is not explicitly recorded as taking a course, it is assumed they are not taking that course.

2. Entity Types

Entity: Person

• Description: Represents a distinct individual.
• Reference Mode: ID
  • Type: Integer
  • Format or Length: Not specified
• Entity Type Specific Constraints:
  • This entity is primarily identified by its ID reference mode.
  • Unique Identification: A Person is also uniquely identified by the combination of values playing the roles: 'Name' in 'Person has FirstName', 'LastName' in 'Person has LastName', 'DateOfBirth' in 'Person was born on DateOfBirth', and 'PlaceOfBirth' in 'Person was born in PlaceOfBirth'.
• Example: A Person identified by ID '101' named 'Alice Smith', born on '1990-05-15' in 'New York'.
• Counter-Example: Two distinct Persons, Person ID '101' and Person ID '102', both having FirstName 'Alice', LastName 'Smith', DateOfBirth '1990-05-15', and PlaceOfBirth 'New York'. This would violate the 'PersonUniqueness' constraint.
• Notes: This constraint provides an alternative or additional way to identify a Person beyond their internal ID. It implies that the combination of these four attributes is a natural key for Person.

Entity: Student

• Description: Represents a distinct individual who is enrolled in studies.
• Reference Mode: ID
  • Type: Not specified (implicitly Integer, inherited from Person)
  • Format or Length: Not specified
• Entity Type Specific Constraints:
  • This entity type inherits its identity from its supertype, Person. This means a Student is identified in the same way as a Person.
  • This entity is primarily identified by its ID reference mode.
• Participates in Fact Types:
  • Student hasLibraryAccess
  • Student takes Course during Semester
• Subtype Of / Supertypes:
  • Subtype of: Person
  • Supertypes of: GradStudent, UnderGradStudent
• Example: A Student identified by ID '201' (who is also a Person).
• Counter-Example: [Provide a relevant counter-example if constraints apply]
• Notes:

Entity: Course

• Description: Represents a distinct academic course.
• Reference Mode: Code
  • Type: Text
  • Format or Length: Not specified
• Entity Type Specific Constraints:
  • This entity is primarily identified by its Code reference mode.
• Participates in Fact Types:
  • GradStudent is TA for Course
  • Student takes Course during Semester
• Subtype Of / Supertypes:
  • No direct supertype or subtype relationships defined.
• Example: A Course identified by Code 'CS101' (e.g., 'Introduction to Computer Science').
• Counter-Example: [Provide a relevant counter-example if constraints apply]
• Notes:

Entity: Semester

• Description: Represents a distinct academic period.
• Reference Mode: Name
  • Type: Text
  • Format or Length: Not specified
• Entity Type Specific Constraints:
  • This entity is primarily identified by its Name reference mode.
• Participates in Fact Types:
  • Student takes Course during Semester
• Subtype Of / Supertypes:
  • No direct supertype or subtype relationships defined.
• Example: A Semester identified by Name 'Fall 2023'.
• Counter-Example: [Provide a relevant counter-example if constraints apply]
• Notes:

Entity: GradStudent

• Description: Represents a distinct individual who is a graduate student.
• Reference Mode: ID
  • Type: Not specified (implicitly Integer, inherited from Student)
  • Format or Length: Not specified
• Entity Type Specific Constraints:
  • This entity type inherits its identity from its supertype, Student. This means a GradStudent is identified in the same way as a Student.
  • This entity is primarily identified by its ID reference mode.
• Participates in Fact Types:
  • GradStudent grades Paper
  • GradStudent writes Paper
  • GradStudent is TA for Course
  • GradStudent advises GradStudent
• Subtype Of / Supertypes:
  • Subtype of: Student
• Example: A GradStudent identified by ID '301' (who is also a Student and a Person).
• Counter-Example: [Provide a relevant counter-example if constraints apply]
• Notes:

Entity: Paper

• Description: Represents a distinct academic paper.
• Reference Mode: Name
  • Type: Text
  • Format or Length: Not specified
• Entity Type Specific Constraints:
  • This entity is primarily identified by its Name reference mode.
• Participates in Fact Types:
  • GradStudent grades Paper
  • GradStudent writes Paper
• Subtype Of / Supertypes:
  • No direct supertype or subtype relationships defined.
• Example: A Paper identified by Name 'Deep Learning in NLP'.
• Counter-Example: [Provide a relevant counter-example if constraints apply]
• Notes:

Entity: UnderGradStudent

• Description: Represents a distinct individual who is an undergraduate student.
• Reference Mode: ID
  • Type: Not specified (implicitly Integer, inherited from Student)
  • Format or Length: Not specified
• Entity Type Specific Constraints:
  • This entity type inherits its identity from its supertype, Student. This means an UnderGradStudent is identified in the same way as a Student.
  • This entity is primarily identified by its ID reference mode.
• Participates in Fact Types:
  • None directly, but may participate through supertype/subtype relationships.
• Subtype Of / Supertypes:
  • Subtype of: Student
• Example: An UnderGradStudent identified by ID '401' (who is also a Student and a Person).
• Counter-Example: [Provide a relevant counter-example if constraints apply]
• Notes:

3. Value Types

Value Type: FirstName

• Description: Represents a specific kind of data value that can be associated with entities.
• Data Type: Text
• Length or Format (if applicable): Not specified
• Allowed Value Range: No specific range or enumeration defined, typically constrained by the data type.
• Used In Fact Types:
  • Person has FirstName
• Example Value: 'Alice'
• Invalid Value Example: [Provide a relevant invalid example value if constraints apply]
• Notes:

Value Type: LastName

• Description: Represents a specific kind of data value that can be associated with entities.
• Data Type: Text
• Length or Format (if applicable): Not specified
• Allowed Value Range: No specific range or enumeration defined, typically constrained by the data type.
• Used In Fact Types:
  • Person has LastName
• Example Value: 'Smith'
• Invalid Value Example: [Provide a relevant invalid example value if constraints apply]
• Notes:

Value Type: DateOfBirth

• Description: Represents a specific kind of data value that can be associated with entities.
• Data Type: Date
• Length or Format (if applicable): Not specified
• Allowed Value Range: No specific range or enumeration defined, typically constrained by the data type.
• Used In Fact Types:
  • Person was born on DateOfBirth
• Example Value: '1990-05-15'
• Invalid Value Example: 'Not a Date' (violates data type)
• Notes:

Value Type: PlaceOfBirth

• Description: Represents a specific kind of data value that can be associated with entities.
• Data Type: Text
• Length or Format (if applicable): Not specified
• Allowed Value Range: No specific range or enumeration defined, typically constrained by the data type.
• Used In Fact Types:
  • Person was born in PlaceOfBirth
• Example Value: 'New York'
• Invalid Value Example: [Provide a relevant invalid example value if constraints apply]
• Notes:

4. Fact Types

Fact Type: Person has FirstName

• Description (Reading Text): This fact type expresses that 'an instance of Person has an instance of FirstName'.
• Roles:
  • Person played by Person (This role is mandatory).
  • Name played by FirstName (This role is optional).
• Constraints Within This Fact Type:
  • Mandatory Roles: Every Person must play the role of 'Person' in this fact type. This means you cannot have a Person that does not participate in this relationship.
  • Internal Uniqueness: Each Person can participate in this fact type at most once. For example, a 'Person' can only 'be has' once.
  • Ring Properties: Not applicable.
• Objectification: No, this fact type is not treated as an entity.
• Valid Example: Person (ID: 101) has FirstName 'Alice'.
• Counter-Example: Person (ID: 101) has FirstName 'Alice' AND Person (ID: 101) has FirstName 'Bob'. This violates the uniqueness constraint on the 'Person' role, as a Person can only have one first name.
• Notes:

Fact Type: Student hasLibraryAccess

• Description (Reading Text): This fact type expresses that 'an instance of Student hasLibraryAccess'.
• Roles:
  • Student played by Student (This role is optional).
• Constraints Within This Fact Type:
  • Mandatory Roles: All roles are optional, meaning an instance of the role player is not required to participate in this fact type.
  • Internal Uniqueness: No internal uniqueness constraint is explicitly defined, meaning multiple instances of the fact with the same values for its roles might be allowed unless other constraints apply.
  • Ring Properties: Not applicable.
• Objectification: No, this fact type is not treated as an entity.
• Valid Example: Student (ID: 201) hasLibraryAccess.
• Counter-Example: [Provide a relevant counter-example population if constraints apply]
• Notes: This is a unary fact type, meaning it describes a property of a single entity (Student) rather than a relationship between multiple entities.

Fact Type: Student takes Course during Semester

• Description (Reading Text): This fact type expresses that 'an instance of Student takes an instance of Course during an instance of Semester'.
• Roles:
  • Student played by Student (This role is optional).
  • Course played by Course (This role is optional).
  • Semester played by Semester (This role is optional).
• Constraints Within This Fact Type:
  • Mandatory Roles: All roles are optional, meaning an instance of the role player is not required to participate in this fact type.
  • Internal Uniqueness: The combination of values for 'Student', 'Course', 'Semester' uniquely identifies each instance of this fact. This means no two instances of this fact can have the same combination of these values.
  • Ring Properties: Not applicable.
• Objectification: No, this fact type is not treated as an entity.
• Valid Example: Student (ID: 201) takes Course (Code: 'CS101') during Semester (Name: 'Fall 2023').
• Counter-Example: Student (ID: 201) takes Course (Code: 'CS101') during Semester (Name: 'Fall 2023') AND Student (ID: 201) takes Course (Code: 'CS101') during Semester (Name: 'Fall 2023'). This is a duplicate fact and violates the uniqueness constraint on the combination of Student, Course, and Semester.
• Notes:

Fact Type: Person has LastName

• Description (Reading Text): This fact type expresses that 'an instance of Person has an instance of LastName'.
• Roles:
  • Person played by Person (This role is mandatory).
  • LastName played by LastName (This role is optional).
• Constraints Within This Fact Type:
  • Mandatory Roles: Every Person must play the role of 'Person' in this fact type. This means you cannot have a Person that does not participate in this relationship.
  • Internal Uniqueness: Each Person can participate in this fact type at most once. For example, a 'Person' can only 'be has' once.
  • Ring Properties: Not applicable.
• Objectification: No, this fact type is not treated as an entity.
• Valid Example: Person (ID: 101) has LastName 'Smith'.
• Counter-Example: Person (ID: 101) has LastName 'Smith' AND Person (ID: 101) has LastName 'Jones'. This violates the uniqueness constraint on the 'Person' role.
• Notes:

Fact Type: Person was born on DateOfBirth

• Description (Reading Text): This fact type expresses that 'an instance of Person was born on an instance of DateOfBirth'.
• Roles:
  • Person played by Person (This role is mandatory).
  • DateOfBirth played by DateOfBirth (This role is optional).
• Constraints Within This Fact Type:
  • Mandatory Roles: Every Person must play the role of 'Person' in this fact type. This means you cannot have a Person that does not participate in this relationship.
  • Internal Uniqueness: Each Person can participate in this fact type at most once. For example, a 'Person' can only 'be was born on' once.
  • Ring Properties: Not applicable.
• Objectification: No, this fact type is not treated as an entity.
• Valid Example: Person (ID: 101) was born on DateOfBirth '1990-05-15'.
• Counter-Example: Person (ID: 101) was born on DateOfBirth '1990-05-15' AND Person (ID: 101) was born on DateOfBirth '1991-01-01'. This violates the uniqueness constraint on the 'Person' role.
• Notes:

Fact Type: Person was born in PlaceOfBirth

• Description (Reading Text): This fact type expresses that 'an instance of Person was born in an instance of PlaceOfBirth'.
• Roles:
  • Person played by Person (This role is mandatory).
  • PlaceOfBirth played by PlaceOfBirth (This role is optional).
• Constraints Within This Fact Type:
  • Mandatory Roles: Every Person must play the role of 'Person' in this fact type. This means you cannot have a Person that does not participate in this relationship.
  • Internal Uniqueness: Each Person can participate in this fact type at most once. For example, a 'Person' can only 'be was born in' once.
  • Ring Properties: Not applicable.
• Objectification: No, this fact type is not treated as an entity.
• Valid Example: Person (ID: 101) was born in PlaceOfBirth 'New York'.
• Counter-Example: Person (ID: 101) was born in PlaceOfBirth 'New York' AND Person (ID: 101) was born in PlaceOfBirth 'Boston'. This violates the uniqueness constraint on the 'Person' role.
• Notes:

Fact Type: GradStudent writes Paper

• Description (Reading Text): This fact type expresses that 'an instance of GradStudent writes an instance of Paper'.
• Roles:
  • GradStudent played by GradStudent (This role is optional).
  • Paper played by Paper (This role is optional).
• Constraints Within This Fact Type:
  • Mandatory Roles: All roles are optional, meaning an instance of the role player is not required to participate in this fact type.
  • Internal Uniqueness: The combination of values for 'GradStudent', 'Paper' uniquely identifies each instance of this fact. This means no two instances of this fact can have the same combination of these values.
  • Ring Properties: Not applicable.
• Objectification: No, this fact type is not treated as an entity.
• Valid Example: GradStudent (ID: 301) writes Paper (Name: 'AI Ethics').
• Counter-Example: GradStudent (ID: 301) writes Paper (Name: 'AI Ethics') AND GradStudent (ID: 301) writes Paper (Name: 'AI Ethics'). This is a duplicate fact and violates the uniqueness constraint on the combination of GradStudent and Paper.
• Notes:

Fact Type: GradStudent grades Paper

• Description (Reading Text): This fact type expresses that 'an instance of GradStudent grades an instance of Paper'.
• Roles:
  • GradStudent played by GradStudent (This role is optional).
  • Paper played by Paper (This role is optional).
• Constraints Within This Fact Type:
  • Mandatory Roles: All roles are optional, meaning an instance of the role player is not required to participate in this fact type.
  • Internal Uniqueness: The combination of values for 'GradStudent', 'Paper' uniquely identifies each instance of this fact. This means no two instances of this fact can have the same combination of these values.
  • Ring Properties: Not applicable.
• Objectification: No, this fact type is not treated as an entity.
• Valid Example: GradStudent (ID: 302) grades Paper (Name: 'Quantum Computing Basics').
• Counter-Example: GradStudent (ID: 302) grades Paper (Name: 'Quantum Computing Basics') AND GradStudent (ID: 302) grades Paper (Name: 'Quantum Computing Basics'). This is a duplicate fact and violates the uniqueness constraint on the combination of GradStudent and Paper.
• Notes:

Fact Type: GradStudent is TA for Course

• Description (Reading Text): This fact type expresses that 'an instance of GradStudent is TA for an instance of Course'.
• Roles:
  • GradStudent played by GradStudent (This role is optional).
  • Course played by Course (This role is optional).
• Constraints Within This Fact Type:
  • Mandatory Roles: All roles are optional, meaning an instance of the role player is not required to participate in this fact type.
  • Internal Uniqueness: The combination of values for 'GradStudent', 'Course' uniquely identifies each instance of this fact. This means no two instances of this fact can have the same combination of these values.
  • Ring Properties: Not applicable.
• Objectification: No, this fact type is not treated as an entity.
• Valid Example: GradStudent (ID: 303) is TA for Course (Code: 'MA101').
• Counter-Example: GradStudent (ID: 303) is TA for Course (Code: 'MA101') AND GradStudent (ID: 303) is TA for Course (Code: 'MA101'). This is a duplicate fact and violates the uniqueness constraint on the combination of GradStudent and Course.
• Notes:

Fact Type: GradStudent advises GradStudent

• Description (Reading Text): This fact type expresses that 'an instance of GradStudent1 advises an instance of GradStudent2'.
• Roles:
  • GradStudent1 played by GradStudent (This role is optional).
  • GradStudent2 played by GradStudent (This role is optional).
• Constraints Within This Fact Type:
  • Mandatory Roles: All roles are optional, meaning an instance of the role player is not required to participate in this fact type.
  • Internal Uniqueness: The combination of values for 'GradStudent1', 'GradStudent2' uniquely identifies each instance of this fact. This means no two instances of this fact can have the same combination of these values.
  • Ring Properties (GradStudentAdvisesGradStudentConstraint): This fact type describes a relationship between instances of the same entity type (e.g., 'GradStudent advises GradStudent'). The following properties apply:
    • Irreflexive: An instance cannot relate to itself. For example, a GradStudent cannot advise themselves.
    • Asymmetric: If A relates to B, then B cannot relate to A. For example, if GradStudent A advises GradStudent B, then GradStudent B cannot advise GradStudent A.
    • Strongly Intransitive: No indirect chains: If A relates to B and B (directly or indirectly) to C, A does not relate to C. For example, if GradStudent A advises GradStudent B, and GradStudent B advises GradStudent C, then GradStudent A cannot advise GradStudent C.
• Objectification: No, this fact type is not treated as an entity.
• Valid Example: GradStudent (ID: 304) advises GradStudent (ID: 305).
• Counter-Example:
  • GradStudent (ID: 304) advises GradStudent (ID: 304). (Violates Irreflexive)
  • GradStudent (ID: 304) advises GradStudent (ID: 305) AND GradStudent (ID: 305) advises GradStudent (ID: 304). (Violates Asymmetric)
  • GradStudent (ID: 304) advises GradStudent (ID: 305) AND GradStudent (ID: 305) advises GradStudent (ID: 306) AND GradStudent (ID: 304) advises GradStudent (ID: 306). (Violates Strongly Intransitive)
• Notes: These constraints are typical for hierarchical or direct reporting/advisory structures where self-loops, reciprocal relationships, or indirect transitive relationships are not allowed.

5. Constraints (Cross Fact Types or Model-Wide)

Constraint: PersonUniqueness

• Scope: This constraint applies to the Person entity type, specifically across the 'Person has FirstName', 'Person has LastName', 'Person was born on DateOfBirth', and 'Person was born in PlaceOfBirth' fact types.
• Constraint Type: External Uniqueness
• Business Meaning: The combination of a Person's FirstName, LastName, DateOfBirth, and PlaceOfBirth must uniquely identify that Person. This means no two distinct persons can share the exact same combination of these four attributes.
• Valid Case:
  • Person (ID: 101) has FirstName 'Alice', LastName 'Smith', DateOfBirth '1990-05-15', PlaceOfBirth 'New York'.
  • Person (ID: 102) has FirstName 'Bob', LastName 'Johnson', DateOfBirth '1985-11-20', PlaceOfBirth 'Los Angeles'.
• Counter-Case:
  • Person (ID: 101) has FirstName 'Alice', LastName 'Smith', DateOfBirth '1990-05-15', PlaceOfBirth 'New York'.
  • Person (ID: 102) has FirstName 'Alice', LastName 'Smith', DateOfBirth '1990-05-15', PlaceOfBirth 'New York'. (This is invalid because two distinct persons have the same identifying attributes).
• Notes: This constraint provides an alternative or additional way to identify a Person beyond their internal ID. It implies that the combination of these four attributes is a natural key for Person.

Constraint: New Exclusion

• Scope: This constraint applies to the roles ''GradStudent' in 'GradStudent grades Paper', 'Paper' in 'GradStudent grades Paper'' and ''GradStudent' in 'GradStudent writes Paper', 'Paper' in 'GradStudent writes Paper''.
• Constraint Type: Exclusion Constraint
• Business Meaning: It is prohibited that a GradStudent grades a Paper and that same GradStudent writes that same Paper. This constraint ensures separation of duties or prevents conflicts of interest.
• Valid Case:
  • GradStudent (ID: 301) writes Paper (Name: 'AI Ethics').
  • GradStudent (ID: 302) grades Paper (Name: 'AI Ethics'). (This is valid because different GradStudents are involved).
• Counter-Case: GradStudent (ID: 301) writes Paper (Name: 'AI Ethics') AND GradStudent (ID: 301) grades Paper (Name: 'AI Ethics'). (This is invalid because the same GradStudent is both writing and grading the same paper).
• Notes: This constraint ensures separation of duties or prevents conflicts of interest.

Constraint: Subset Constraint

• Scope: This constraint applies between the roles ''GradStudent' in 'GradStudent is TA for Course', 'Course' in 'GradStudent is TA for Course'' (subset) and ''Student' in 'Student takes Course during Semester', 'Course' in 'Student takes Course during Semester'' (superset). Specifically, it relates 'GradStudent is TA for Course' to 'Student takes Course during Semester'.
• Constraint Type: Subset Constraint
• Business Meaning: If a GradStudent is a Teaching Assistant (TA) for a specific Course, then that GradStudent must also be taking that same Course (as a Student) during some Semester. This implies that TAs must be enrolled in the courses they assist.
• Valid Case:
  • GradStudent (ID: 303) is TA for Course (Code: 'MA101').
  • Student (ID: 303) takes Course (Code: 'MA101') during Semester (Name: 'Fall 2023'). (This is valid because the TA is also taking the course).
• Counter-Case: GradStudent (ID: 303) is TA for Course (Code: 'MA101'). (No record of Student (ID: 303) taking Course (Code: 'MA101') during any Semester). (This is invalid because a TA must be taking the course they assist).
• Notes: This constraint enforces a prerequisite or a logical dependency between two different types of relationships.

Constraint: GradStudentAdvisesGradStudentConstraint

• Scope: This constraint applies to the 'GradStudent advises GradStudent' fact type, specifically to the roles 'GradStudent1' and 'GradStudent2'.
• Constraint Type: Ring Constraint (Irreflexive, Asymmetric, Strongly Intransitive)
• Business Meaning: This constraint defines specific properties for the 'advises' relationship between GradStudents:
  • Irreflexive: An instance cannot relate to itself. For example, a GradStudent cannot advise themselves.
  • Asymmetric: If A relates to B, then B cannot relate to A. For example, if GradStudent A advises GradStudent B, then GradStudent B cannot advise GradStudent A.
  • Strongly Intransitive: No indirect chains: If A relates to B and B (directly or indirectly) to C, A does not relate to C. For example, if GradStudent A advises GradStudent B, and GradStudent B advises GradStudent C, then GradStudent A cannot advise GradStudent C.
• Valid Case: GradStudent (ID: 304) advises GradStudent (ID: 305).
• Counter-Case:
  • GradStudent (ID: 304) advises GradStudent (ID: 304). (Violates Irreflexive)
  • GradStudent (ID: 304) advises GradStudent (ID: 305) AND GradStudent (ID: 305) advises GradStudent (ID: 304). (Violates Asymmetric)
  • GradStudent (ID: 304) advises GradStudent (ID: 305) AND GradStudent (ID: 305) advises GradStudent (ID: 306) AND GradStudent (ID: 304) advises GradStudent (ID: 306). (Violates Strongly Intransitive)
• Notes: These constraints are typical for hierarchical or direct reporting/advisory structures where self-loops, reciprocal relationships, or indirect transitive relationships are not allowed.

Constraint: New Subtype Exclusive-Or

• Scope: This constraint applies to the supertype Student and its subtypes: GradStudent, UnderGradStudent.
• Constraint Type: Subtype Exclusive-Or Constraint
• Business Meaning: Every instance of a Student must be an instance of *exactly one* of the specified subtypes (GradStudent, UnderGradStudent). It cannot be an instance of none of them, nor can it be an instance of more than one of them simultaneously.
• Valid Case:
  • Student (ID: 201) is an UnderGradStudent.
  • Student (ID: 202) is a GradStudent.
• Counter-Case:
  • Student (ID: 203) is neither a GradStudent nor an UnderGradStudent. (Violates the 'or' part - must be one)
  • Student (ID: 204) is both a GradStudent and an UnderGradStudent. (Violates the 'exclusive' part - cannot be both)
• Notes: This constraint ensures that the subtypes form a complete and disjoint partition of their supertype. Every Student must be either a GradStudent or an UnderGradStudent, but not both.

6. Derivation Rules

This model primarily defines base facts and constraints. There are no explicit derivation rules for new fact types or subtypes defined within the provided JSON structure. However, the subtype relationships inherently imply certain derivations:

Derivation: GradStudent is a Student (and thus a Person)

• Derived From: The subtype connection 'GradStudent' is a subtype of 'Student'.
• Logical Condition: If an entity is a 'GradStudent', then it is also a 'Student'. Since 'Student' is a 'Person', a 'GradStudent' is also a 'Person'.
• Business Interpretation: All graduate students are also considered students, and by extension, persons. They inherit the characteristics and identification of a Student and a Person.
• Example Where Derived Value Applies: If 'GradStudent (ID: 301)' exists, then 'Student (ID: 301)' and 'Person (ID: 301)' also exist and refer to the same individual.
• Example Where It Does Not Apply: A 'Student' who is an 'UnderGradStudent' is not a 'GradStudent'.

Derivation: UnderGradStudent is a Student (and thus a Person)

• Derived From: The subtype connection 'UnderGradStudent' is a subtype of 'Student'.
• Logical Condition: If an entity is an 'UnderGradStudent', then it is also a 'Student'. Since 'Student' is a 'Person', an 'UnderGradStudent' is also a 'Person'.
• Business Interpretation: All undergraduate students are also considered students, and by extension, persons. They inherit the characteristics and identification of a Student and a Person.
• Example Where Derived Value Applies: If 'UnderGradStudent (ID: 401)' exists, then 'Student (ID: 401)' and 'Person (ID: 401)' also exist and refer to the same individual.
• Example Where It Does Not Apply: A 'Student' who is a 'GradStudent' is not an 'UnderGradStudent'.

7. Inconsistencies or Gaps

• Contradictory Mandatory/Optional Roles for Person Attributes: The verbalizations for 'Person has FirstName', 'Person has LastName', 'Person was born on DateOfBirth', and 'Person was born in PlaceOfBirth' state that the 'Person' role is mandatory and the attribute role is optional, with an internal uniqueness constraint on the 'Person' role, implying an "exactly one" relationship. However, the model diagram might visually represent these as optional roles for the attributes themselves. It's crucial to ensure the visual representation and the verbalization are consistent, as an optional attribute role combined with a mandatory person role and uniqueness on the person role would still enforce "exactly one" (i.e., the person must have exactly one of that attribute). If the intent is truly optional, the uniqueness constraint on the person role should be removed.
• Unspecified Reference Mode Data Type for Subtypes: The 'Student', 'GradStudent', and 'UnderGradStudent' entity types inherit their identity from 'Person' (via 'Student'). While 'Person' has a 'refMode' with `dataType: "Integer"`, the inherited reference modes for 'Student', 'GradStudent', and 'UnderGradStudent' only specify `name: "ID"` without an explicit `dataType`. While implicitly inherited, explicitly stating it or ensuring consistency would improve clarity.
• Unary Fact Type 'Student hasLibraryAccess': This fact type has only one role, which is optional. This means it simply records whether a student *has* library access, but it doesn't require all students to have or not have it. This is a valid modeling choice but should be clear in its interpretation.

8. Summary and Interpretation Integrity

• Does the model express complete business logic? The model captures a significant portion of common university domain logic, including person details, student enrollment, and academic relationships (TA, advising, paper writing/grading). However, there are some areas that could be further elaborated or clarified, particularly regarding the implications of optional identifying attributes and the precise scope of the 'PersonUniqueness' constraint.
• Are all constraints and roles logically consistent? Generally, yes. The constraints (uniqueness, exclusion, subset, ring, exclusive-or subtype) appear to be logically sound given their intended business meaning. The main point of potential inconsistency or ambiguity lies in the 'PersonUniqueness' constraint combined with the optional roles for the identifying attributes, which could lead to data integrity issues if not carefully managed.
• Are derived facts and subtypes inferable from the base facts and constraints? Yes, the derivations for 'GradStudent is a Student (and thus a Person)' and 'UnderGradStudent is a Student (and thus a Person)' are directly inferable from the defined subtype relationships, which is a key strength of ORM.