@prefix psr: <http://data.loterre.fr/ark:/67375/PSR> .
@prefix skos: <http://www.w3.org/2004/02/skos/core#> .

psr:-B373Q2P1-V
  skos:prefLabel "combinatorics"@en, "combinatoire"@fr ;
  a skos:Concept ;
  skos:narrower psr:-H2HH6NWV-C .

psr:-H2HH6NWV-C
  skos:exactMatch <https://en.wikipedia.org/wiki/Langford_pairing> ;
  a skos:Concept ;
  skos:prefLabel "suite de Langford"@fr, "Langford sequence"@en ;
  skos:broader psr:-B373Q2P1-V ;
  skos:inScheme psr: ;
  skos:related psr:-TVV81SX3-J ;
  skos:altLabel "Langford's problem"@en, "Langford pairing"@en ;
  skos:definition """In combinatorial mathematics, a Langford pairing, also called a Langford sequence, is a permutation of the sequence of 2<i>n</i> numbers 1, 1, 2, 2, ..., <i>n</i>, <i>n</i> in which the two 1s are one unit apart, the two 2s are two units apart, and more generally the two copies of each number <i>k</i> are <i>k</i> units apart. Langford pairings are named after C. Dudley Langford, who posed the problem of constructing them in 1958. 
<br/>(Wikipedia, The Free Encyclopedia, <a href="https://en.wikipedia.org/wiki/Langford_pairing">https://en.wikipedia.org/wiki/Langford_pairing</a>)"""@en .

psr:-TVV81SX3-J
  skos:prefLabel "Skolem sequence"@en, "suite de Skolem"@fr ;
  a skos:Concept ;
  skos:related psr:-H2HH6NWV-C .

psr: a skos:ConceptScheme .