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:Robert M. Ricketts developed the Utility arch in 1950s and it is considered to be an integral part of the Bioprogressive Therapy in Orthodontics . Sentence 2:nan

SOLUTION: SINGLE_S_COORD_ANAPHORA

PROBLEM: Sentence 1:Scott received his B.S. degree from Massachusetts Institute of Technology and graduated with a J.D. from the University of California , Los Angeles . Sentence 2:He has taught as a law professor at Southwestern Law School .

SOLUTION: PAIR_ANAPHORA

PROBLEM: Sentence 1:Ambulocetus was the size of a male sea lion , much larger than Pakicetus . Sentence 2:Thewissen et al. estimated the body weight of Ambulocetus at 141 -- 235 kg ( 311 -- 518 lb ) , while Philip D. Gingerich estimated it at 720 kg ( 1,590 lb ) .

SOLUTION:
PAIR_ANAPHORA