TASK DEFINITION: In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.
PROBLEM: Billy McKee ( ; 12 November 1921 – 11 June 2019 ) was an Irish republican .

SOLUTION: Billy McKee ( ; 12 November 1921 – 11 June 2019 ) was an Irish republican and a founding member and leader of the Provisional Irish Republican Army ( PIRA ) .

PROBLEM: The Hondo and the Sarstoon River make the northern and southern border .

SOLUTION: The undulating courses of two rivers , the Hondo and the Sarstoon River , define much of the course of the country 's northern and southern boundaries .

PROBLEM: A Page replacement algorithm is an algorithm that decides which pages should be written to disk or file , when a new page needs to be allocated .

SOLUTION:
In a computer operating system that uses paging for virtual memory management , page replacement algorithms decide which memory pages to page out , sometimes called swap out , or write to disk , when a page of memory needs to be allocated .