Frequently Asked Questions #

Please also note the current limitations.

I can’t find a property used in the data in the exploration menu #

We use a heuristic for the selection of a single property in case multiple equivalent properties or mutually inverse properties exist. More precisely, when properties are equivalent to each other, only one of them is displayed in the exploration menu, namely the one with the smallest IRI according to their lexicographical ordering. The same applies to mutually inverse properties. Note that this might change in the future and is planned to be configurable.

What resources are found in [No class]? #

[No class] includes all IRIs that are used like an individual resource, but for which no class type information can be derived according to the implemented inference fragment other than rdfs:Resource, owl:NamedIndividual, or owl:Thing.

SemSpect seems to freeze during index generation #

If SemSpect freezes (no CPU load) when computing the indices and does not issue an error message or warning, it may have run out of memory. Please abort and try again using:

  • the two-pass generation approach ad described in the index generation configuration, which requires more time but consumes less main memory by generating the compressed dictionary and index one after the other,

  • a larger JVM heap space, which can be specified by -Xmx either as option to JDK_JAVA_OPTIONS or to SEMSPECT_JDK_OPTIONS in case this setting should only apply to SemSpect. All variants work for both provided command line scripts (semspect.* and semspect-spring.*). For example in case of Linux/OSX with export SEMSPECT_JDK_OPTIONS=-Xm32g.