Given two noun phrases (arguments) and relationship between them, form a sentence that expresses theses arguments with the given relationship.

[Q]: Relationship: 'be city of', Argument/Subject 1: 'dalla', Argument/Subject 2: 'texa'
[A]: Dallas is the second largest city in Texas with approximately 1.2 million people .


[Q]: Relationship: 'be city in', Argument/Subject 1: 'samarkand', Argument/Subject 2: 'uzbekistan'
[A]: Samarkand is the third-largest city in Uzbekistan and the capital of Samarqand Province .


[Q]: Relationship: 'be head of', Argument/Subject 1: 'president', Argument/Subject 2: 'executive'
[A]:
The service has been dubbed Derivatives Collateral Net and automatically aggregates and nets the overall collateral obligations of its participants , explains Art Certosimo , executive vice president and head of Broker-Dealer Services at the bank .