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How to Add a Data Property

A data property is a boolean characteristic of a MathModDB entity — for example is dimensional or is physical constant. When a user selects such a property in the RDMO interview, MaRDMO validates the selection, writes it to the questionnaire, checks it before export, and maps it to a Wikibase statement on the MaRDI Portal.

Properties come in two flavours:

  • Class-dependent — the corresponding MaRDI Portal item has a different name per entity class. Example: is dimensional maps to "dimensional model", "dimensional formula", "dimensional quantity", "dimensional quantity kind" — separate Wikibase items for each class.
  • Class-independent — one Wikibase item is used regardless of entity class. Example: is physical constant maps to "physical constant" for every entity class that supports it.

The two walkthroughs below use these properties as concrete examples. Both properties are part of the MaRDMO Catalogs for detailed and basic documentation of mathematical models.

!!! note "Quantity and Quantity Kind" The entity classes Quantity and Quantity Kind are treated together in the backend under the key quantity. They share a single pair of SPARQL query files (quantity_mardi.sparql and quantity_wikidata.sparql), where both item types are covered via a UNION pattern.

Case 1 — Class-Dependent: is dimensional

Step 1a — Add the Option to RDMO

Create a new option with the URI https://rdmo.mardi4nfdi.de/terms/options/mathmoddb/is-dimensional and add it to each relevant optionset in RDMO. For is dimensional the relevant optionsets are:

  • https://rdmo.mardi4nfdi.de/terms/options/model-properties
  • https://rdmo.mardi4nfdi.de/terms/options/formulation-properties
  • https://rdmo.mardi4nfdi.de/terms/options/quantity-properties

See How to Create a New Option and How to Create a New Optionset for further information.

Step 1b — Register the Option in model/data/mapping.json

Add an entry to model/data/mapping.json. This file maps MathModDB property keys to their RDMO option URIs and human-readable labels:

{"key": "is_dimensional", "url": "https://rdmo.mardi4nfdi.de/terms/options/mathmoddb/is-dimensional", "label": "is dimensional"}

Step 2 — Register MaRDI Portal QIDs

Add one entry per entity class to data/items.json (productive portal) and data/items_staging.json (staging portal, for testing purposes):

data/items.json:

"dimensional model":         "Q6775551",
"dimensional formula":       "Q6775550",
"dimensional quantity":      "Q6775552",
"dimensional quantity kind": "Q6775553"

data/items_staging.json:

"dimensional model":         "Q13324",
"dimensional formula":       "Q13323",
"dimensional quantity":      "Q13325",
"dimensional quantity kind": "Q13326"

Step 3 — model/constants.py

3a — Mutual exclusion pair (is dimensional and is dimensionless cannot both be true at the same time):

data_properties_check = [
    ...
    ('is_dimensionless', 'is_dimensional'),
]

3b — Entity classes that carry this property (model, formula, quantity, quantity kind):

data_properties_per_class = {
    'model':       [..., 'is_dimensional'],
    'formulation': [..., 'is_dimensional'],
    'quantity':    [..., 'is_dimensional'],
}

3c — Register as class-dependent. The second element is the item name prefix; MaRDMO appends the entity class name automatically to look up the correct Wikibase item ("dimensional model", "dimensional formula", etc.):

DEPENDENT_PROPERTIES = [
    ...
    ('is_dimensional', 'dimensional'),
]

Step 4 — SPARQL Queries

For each entity class the property applies to, edit the corresponding files in model/queries/ — both the MaRDI and Wikidata variants, and both the full and -basics variants where they exist.

Affected files for is dimensional:

Entity class Files
Model model_mardi.sparql, model_wikidata.sparql, model-basics_mardi.sparql, model-basics_wikidata.sparql
Formula formulation_mardi.sparql, formulation_wikidata.sparql, formulation-basics_mardi.sparql, formulation-basics_wikidata.sparql
Quantity + Quantity Kind quantity_mardi.sparql, quantity_wikidata.sparql

MaRDI Portal queries (*_mardi.sparql): add ?is_dimensional to the SELECT and GROUP BY clauses. For model and formula files, add a single OPTIONAL block with a trailing BIND:

OPTIONAL {{ ?id wdt:{instance of} wd:{dimensional model}. BIND("True" AS ?is_dimensional_raw) }}
    BIND(COALESCE(?is_dimensional_raw, "False") AS ?is_dimensional)

Use {dimensional formula} in the formula files. For the quantity file, both item types are combined via UNION since only one file covers both:

OPTIONAL {{ {{ ?id wdt:{instance of} wd:{dimensional quantity}. }} UNION {{ ?id wdt:{instance of} wd:{dimensional quantity kind}. }} BIND("True" AS ?is_dimensional_raw) }}
    BIND(COALESCE(?is_dimensional_raw, "False") AS ?is_dimensional)

Wikidata queries (*_wikidata.sparql): the items "dimensional model", "dimensional formula", "dimensional quantity", and "dimensional quantity kind" do not currently exist in Wikidata, so there is nothing to add to the Wikidata SPARQL queries. Should these items be created in Wikidata in the future, the corresponding blocks can be added at that point using the actual Wikidata QIDs.

Case 2 — Class-Independent: is physical constant

Step 1a — Add the Option to RDMO

Create a new option with the URI https://rdmo.mardi4nfdi.de/terms/options/mathmoddb/is-physical-constant and add it to the relevant optionset. For is physical constant the relevant optionset is:

  • https://rdmo.mardi4nfdi.de/terms/options/quantity-properties

See How to Create a New Option and How to Create a New Optionset for further information.

Step 1b — Register the Option in model/data/mapping.json

{"key": "is_physical_constant", "url": "https://rdmo.mardi4nfdi.de/terms/options/mathmoddb/is-physical-constant", "label": "is physical constant"}

Step 2 — Register MaRDI Portal QIDs

A single item is shared across all entity classes:

data/items.json:

"physical constant": "Q6534290"

data/items_staging.json:

"physical constant": "Q1777"

Step 3 — model/constants.py

3a — Mutual exclusion pairs (is physical constant is mutually exclusive with both is mathematical constant and is chemical constant):

data_properties_check = [
    ...
    ('is_mathematical_constant', 'is_physical_constant'),
    ('is_physical_constant',     'is_chemical_constant'),
]

3b — Entity classes (is physical constant applies to quantities and quantity kinds only):

data_properties_per_class = {
    'quantity': [..., 'is_physical_constant'],
}

3c — Register as class-independent. The second element is the full item name used for all entity classes:

INDEPENDENT_PROPERTIES = [
    ...
    ('is_physical_constant', 'physical constant'),
]

Step 4 — SPARQL Queries

Only the quantity query files need updating: quantity_mardi.sparql and quantity_wikidata.sparql.

Add ?is_physical_constant to SELECT and GROUP BY, then add the OPTIONAL block in the WHERE clause.

MaRDI Portal:

OPTIONAL {{ ?id wdt:{instance of} wd:{physical constant}. BIND("True" AS ?is_physical_constant_raw) }}
    BIND(COALESCE(?is_physical_constant_raw, "False") AS ?is_physical_constant)

Wikidata: "physical constant" exists in Wikidata as Q173227, so the corresponding block should be added to the Wikidata query:

OPTIONAL {{ ?id wdt:P31 wd:Q173227. BIND("True" AS ?is_physical_constant_raw) }}
    BIND(COALESCE(?is_physical_constant_raw, "False") AS ?is_physical_constant)