Implement the Amb Evaluator of section 4.3.3.

Included is the following file:

	Amb_Evaluator.scm

Thank you!
							Lawrence X. Amlord
							  Mar 16th, 2014
							  Xi'an, China
Add my answer to Exercise 4.50.

Included are the following 4 files:

	Exercise_4.50.pdf
	Exercise_4.50.scm
	Exercise_4.50.tm
	Test_for_Exercise_4.50.scm

Thank you!
							Lawrence X. Amlord
							  Mar 17th, 2014
							  Xi'an, China
Add my answer to Exercise 4.51.

Included are the following 2 files:

	Exercise_4.51.scm
	Test_for_Exercise_4.51.scm

Thank you!
							Lawrence X. Amlord
							  Mar 17th, 2014
							  Xi'an, China