Question: What are the mathematical concept which start with the letter u
Paraphrase: What are the numerical concept which begin with the letter u
SPARQL (Wikidata): SELECT DISTINCT ?sbj ?sbj_label WHERE { ?sbj wdt:P31 wd:Q24034552 . ?sbj rdfs:label ?sbj_label . FILTER(STRSTARTS(lcase(?sbj_label), 'u')) . FILTER (lang(?sbj_label) = 'en') } LIMIT 25 
Answer: unit, unit, universe, universe, Urysohn space, Urysohn space, ultrafilter, ultrafilter, ultrafinitism, ultrafinitism, ultralimit, ultralimit, Urysohn universal space, Urysohn universal space