TASK DEFINITION: In this task, you are given two sentences in the English language and your task is to classify them into one of their discourse types. A discourse type is an indicator to classify the given two sentences on the basis of a co-text as well as a relevant context. There are 13 discourse types in total which are 'SINGLE_S_COORD', 'SINGLE_CATAPHORA', 'SINGLE_CONN_INNER', 'SINGLE_APPOSITION', 'SINGLE_VP_COORD', 'SINGLE_CONN_START', 'PAIR_ANAPHORA', 'PAIR_CONN', 'SINGLE_RELATIVE', 'SINGLE_CONN_INNER_ANAPHORA', 'SINGLE_S_COORD_ANAPHORA', 'PAIR_CONN_ANAPHORA' and 'PAIR_NONE'.
PROBLEM: Sentence 1:The YouTube app , which had been a default app on iOS developed by Apple , was removed . Sentence 2:nan

SOLUTION: SINGLE_RELATIVE

PROBLEM: Sentence 1:^ Jump up to : Kwasi Ampene ( 2005 ) . Sentence 2:Female Song Tradition and the Akan of Ghana .

SOLUTION: PAIR_NONE

PROBLEM: Sentence 1:Continuing his search for Donavan , Chris rides on toward the Mexican border and finds Jim with a group of armed farmers from Magdalena hiding on a ridge , hoping to ambush De Toro . Sentence 2:nan

SOLUTION:
SINGLE_CATAPHORA