What the canvas draws¶
What is on a board¶
Every class, object property, data property and individual of the open ontology, imports included, as soon as the OntoBoard tab opens - up to 1,500 terms, the ontology's own first. A term made anywhere in Protégé appears beside its superclass. Hide from board takes one off and keeps it off; More → Show every term brings them back. A board saved by OntoBoard before 1.131.0 keeps the terms chosen then, and says so.
The board is written to <ontology file>.ontoboard.json, beside the ontology, from your first change
to it - a move, a hidden term, a note - and not before: an ontology opened and closed leaves no file.
Until 1.133.0 one was written anyway, as Protégé closed or made the ontology active again, and that
file then kept the outline of the day it was written.
Where things go¶
The board is laid out as an outline (Arrange → Outline):
| Where | |
|---|---|
| Design patterns the ontology imports, or has merged in | a frame each, named after the pattern, in rows along the top |
| Classes - the TBox | trees read top down: a class above its subclasses, centred over them; many leaves under one class in a grid below it; trees side by side, wrapping at about a screen's width |
| A class's restrictions, unions, enumerations | a grey node below the class, with its subclasses |
| Individuals - the ABox | a band below all the classes: each class's individuals under that class, in a column; an individual's values right below it |
| Object properties, data properties | each a frame of its own, right of the classes, as its property hierarchy |
On pizza (86 terms) and MWO (660, with 21 frames), measured in Protégé 5.6.9: no two boxes overlap, and no line passes through a frame neither of its ends is in.
A pattern is found by its terms, too. An ontology that has a library pattern merged into its own file - by Protégé, ROBOT or by hand, with no import and no note left by OntoBoard - gets the pattern's frame when it declares at least two of the pattern's own terms, and they are at least 60% of them. Terms many patterns share, such as an upper ontology's, do not count. Each class is in one frame. Measured in Protégé 5.6.9 since 1.133.0: the pizza ontology as a single file shows 3 patterns, NFDIcore 14 and MWO 19, with no overlaps. A board saved before 1.133.0 gets them with Arrange → Outline.
Description logic¶
Arrows and grey nodes are written in description logic:
| On the board | Means | Line |
|---|---|---|
∃ R |
some: every A relates by R to some B | solid blue |
∀ R |
only: whatever an A relates to by R is a B | dashed, diamond head |
≥ n R, ≤ n R, = n R |
at least, at most, exactly n | dotted, round head |
∃ R.{…} |
has the value: the arrow points at the individual | solid blue |
¬ R |
a negative assertion between two individuals | grey, dashed |
⊓, ⊔, ¬, { … } |
and, or, not, one of - a grey node, its parts hanging off it | |
R⁻ |
the inverse of R | |
≡ before a name |
a defined class |
A subclass arrow (⊑) is a hollow-headed solid line; an equivalence is two of them. The legend, ? on the toolbar, has every line.
From the description view to the board. Select a line in Protégé's description of a class - SubClass Of: ∃ hasTopping.Cheese - and the board selects the arrows that draw it, with the terms at their ends, and scrolls to them.
Drawn¶
Every logical axiom in both ontologies - 921 of 921 in MWO, 529 of 529 in NFDIcore.
| Axiom | Drawn as | On MWO |
|---|---|---|
SubClassOf(A B) |
hollow-headed arrow | 391 |
SubClassOf(A, R some/only/min/max/exactly B) |
arrow labelled ∃ R, ∀ R, ≥ n R, ≤ n R or = n R, each with its own line |
86 |
SubClassOf(A, B ⊓ …) |
an arrow to each named conjunct, the rest as below | 36 |
EquivalentClasses(A B) |
two hollow arrows | - |
EquivalentClasses(A, R some B) and other definitions |
as SubClassOf, both ways |
51 |
| An equivalence between two restrictions | two expression nodes joined both ways | 1 |
| Union, complement, enumeration, nested filler, inverse-property restriction | a grey node for the expression, its operands hanging off it | 77 nodes |
ObjectPropertyDomain / ObjectPropertyRange |
from the property's node, long-dashed, labelled domain / range; a union as its own node |
57 / 55 |
DataPropertyDomain / DataPropertyRange |
the same, the range to its datatype | 3 / 3 |
DisjointClasses |
dashed red line, no arrowheads, one per pair; a restriction as its node | 17 axioms |
SubObjectPropertyOf / SubDataPropertyOf |
arrow between property nodes | 49 |
EquivalentObjectProperties |
two sub-property arrows - or an inverse line, for p ≡ inverse(q) |
1 |
InverseObjectProperties |
dashed line, arrowheads both ends | 41 |
| Property characteristics | a suffix on the property's label - (transitive), (functional) … |
27 |
SubPropertyChainOf |
a chain: R o S node with numbered links |
5 |
ClassAssertion |
rdf:type arrow |
50 |
ObjectPropertyAssertion |
arrow between two individuals, labelled with the property | 5 |
HasKey |
an arrow to each key property, labelled key |
0 |
| SWRL rule | a node reading the rule - rule: a(?x) ∧ b(?x, ?y) → c(?x) - with a dotted if line from each term its body uses and a then line to each term it concludes |
4 |
SubClassOf(R some B, A) - a scoped domain |
an arrow from A to B labelled R (scoped domain) |
- |
Any other SubClassOf whose subclass is an expression |
the expression as its node, a hollow arrow from it | - |
DisjointUnion(A B C) |
hollow arrows from B and C to A, and a disjointness line between B and C | - |
DisjointObjectProperties / DisjointDataProperties |
a disjointness line between the property nodes | - |
SameIndividual / DifferentIndividuals |
a line labelled same as / different from, one per pair |
- |
ObjectPropertyAssertion that is negative |
an arrow labelled not R |
- |
DataPropertyAssertion |
a box holding the value, and an arrow to it from the individual, labelled with the property; not R for a negative one |
- |
Every arrow of the first kinds - subclass, type, and an existential restriction - says something the ontology entails: a test turns each back into the axiom it claims and checks it with HermiT, on every version of the pizza example and on the shapes that were once drawn wrongly.
Whole of MWO: 749 nodes and 1,252 edges. Class expressions can be switched off under More → Show class expressions; then the 47 axioms whose shape needs an expression node are not drawn.
On a large board¶
More than 150 relations, and lines drawn alike become a mesh across the whole board. So on a board that size:
- disjointness, domains and ranges are drawn for the term in focus - select it - rather than all at once (106 and 118 lines on MWO);
- the other relations, and any line longer than 1,600 px, are drawn faintly until one of their ends is selected;
- selecting a term brings it and everything it is connected to forward and fades the rest (Focus on the toolbar turns this off).
More → Show on the board switches object properties, data properties, individuals, imported terms and rules off and on. A class can be folded - right-click, Collapse subclasses - and then shows how many terms it holds.
Working on the board¶
- A defined class - one with an equivalence, so the reasoner can find its members - has
≡before its name. The legend (? on the toolbar) has it. - Show only this and its neighbours: right-click a term. Everything else leaves the board until Escape, or More → Show the whole board.
- Fold a class with right-click → Collapse subclasses; More → Expand every folded class opens them all again.
- Rules: double-click a rule's node to read it set out - If, each condition on a line, then, each conclusion. More → Show on the board → Rules takes them off a board that has many.
- Keys, as in a mind map: Tab makes a subclass of the selected class, Enter a sibling; double-click empty board for a new class. ? → Keyboard shortcuts lists them all.
Not drawn¶
| Why | |
|---|---|
| Annotations | On the hover and in the left panel's editable frames; rdfs:label is already the node's name. |
Consequences worth knowing¶
- One hop means "the other end of an edge the canvas would draw", plus the property an arrow stands for. A domain and a range are drawn from the property's own node, so a class reaches the classes at the property's other end through the property.
- An expression node is not a term: it has no IRI, clicking it selects nothing in Protégé, and an arrow ending on one cannot be retracted from the canvas - edit the class's definition in the description view instead. The same holds for a rule's node and for a domain that is a union.
- The DOT export carries every node and edge kind, expression and rule nodes included.
- A node with no saved position - a new term, or a derived node such as a datatype, a class expression or a rule - is placed beside its parent or in the first free slot, and keeps that place from then on.
- Redrawing after an edit changes only what changed: on MWO, 12 ms when nothing did, and 110 ms to project and redraw after a class is added. The board is not redrawn while it is not on screen; it catches up when it is shown.