PSPARQL regular expression patterns


Let I be the set of irirefs, B be the set of blanks, and X be the set of variables. The regular expression patterns used in the PSPARQL query language are constrcuted inductively over IBX in the following way:

Where +A denotes the positive closure of A, *A denotes the Kleene closure of A, !a denotes the negation of a, A|B denotes the disjunction of A and B, and A.B denotes the concatenation of A and B.


The following regular expression pattern generates words of length at least one that contains train or bus repeated many times:

+(train | bus)

The following regular expression pattren generates words, which are of length two, that contains any symbol other than train followed by avion:

!train . avion

Constrained regular expressions

The constrained regular expressions allowed in CPSPARQL Grammar are the ones constructed over the set of urirefs, blanks, and variables.

We use { and } to denote the begining and the end of a constrained regular expression that will be applied to the constraint. The inverse, positive and kleene operators will be prefixed. For example, + ( {-ex:from} % const1 % . ex:to ) is a constraint regular expression, the constraint in this example will be applied to the part -ex:from. See also the Grammar.

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