In 2021, how many papers did the authors of 'Motion Strategy Using Opponent Player's Serial Learning for Air-Hockey Robots' publish?
Count the papers published by the authors of 'Motion Strategy Using Opponent Player's Serial Learning for Air-Hockey Robots' in 2021.
SELECT DISTINCT (COUNT(?answer) AS ?count) WHERE { <https://dblp.org/rec/conf/iros/FukudaTN21> <https://dblp.org/rdf/schema#authoredBy> ?x . ?answer <https://dblp.org/rdf/schema#authoredBy> ?x . ?answer <https://dblp.org/rdf/schema#yearOfPublication> '2021' }
<https://dblp.org/rec/conf/iros/FukudaTN21>