A university wants to develop a database for managing information about students, graduate students, Ph.D. students and professors. Student information should include the students name, age, sex and address of family residence. The university is also interested in maintaining student information about city and state of birth and all cities and states where students have lived with their families along with the number of years they lived in each location.

For each course a student has passed, we wish to manage the course name and course identifier. In addition, we would like to maintain information about the professor who taught the course, the grade the student received in the course and the semester the course was taken.

We also desire to track courses that students are attending in the current academic year. For each course, we should track information such as the name of the course and the course identifier. We should track the student schedule for each course. Each course meets one day a week in a specified room and during a specified time period.

We desire to track other information related to graduate students. Graduate students have a faculty advisor and a total number of credit hours to date we wish to track. For Ph.D. students, we wish to represent their research area and the title of their thesis.

Finally, for professors, we want to represent their last name. We also wish to represent their age, city and state of birth. For professors, we should also represent the name and code for the department they belong to along with their phone extension number on campus. Their title, marital status and research area should also be tracked.

Develop an ER conceptual data model for a university database system. Make appropriate use of all aspects of ER data modeling, including entity, attribute and relationship types and sub-types with relationship cardinality constraints defined in the ER diagram. Keys should also be identified.