Students with Zipcode and Birth Month Alice 19403 Mar Bob 19111 Sept Brian 19403 June Chelsea 19027 Feb Cong 19446 Oct Dave 19403 Feb Jenna 19124 Dec Jessica 19135 Sept John 19446 Jan Kate 19446 Apr Kevin 19135 July Matt 18931 Mar Mellisa 19027 Jan Mike 19135 Nov Song 19446 Sept Ted 19403 Feb Yuki 19446 Aug

Equivalence Relations (a,b) R1 iff a resides in the same zipcode area as b (a,b) R2 iff a was born in the same month as b

Students by Zipcode Matt 18931 Chelsea 19027 Mellisa 19027 Bob 19111 Jenna 19124 Jessica 19135 Kevin 19135 Mike 19135 Alice 19403 Brian 19403 Dave 19403 Ted 19403 Cong 19446 John 19446 Kate 19446 Song 19446 Yuki 19446

Equivalence Classes by Zip Codes {Matt} {Chelsea, Melissa} {Bob} {Jenna} {Jessica, Kevin, Mike} {Alice, Brian, Dave, Ted} {Cong, John, Kate, Song, Yuki}

Equivalence Classes by Birth Month {John, Melissa} {Chelsea, Dave, Ted} {Alice, Matt} {Kate} {Brian} {Kevin} {Yuki} {Bob, Jessica, Song} {Cong} {Mike} {Jenna}

Equivalence Classes By Zipcode {Matt} {Chelsea, Melissa} {Bob} {Jenna} {Jessica, Kevin, Mike} {Alice, Brian, Dave, Ted} {Cong, John, Kate, Song, Yuki} By Birthmonth {John, Melissa} {Chelsea, Dave, Ted} {Alice, Matt} {Kate} {Brian} {Kevin} {Yuki} {Bob, Jessica, Song} {Cong} {Mike} {Jenna}