1. Students with Zipcode and Birth Month
Alice Mar
Bob Sept
Brian June
Chelsea Feb
Cong Oct
Dave Feb
Jenna Dec
Jessica Sept
John Jan
Kate Apr
Kevin July
Matt Mar
Mellisa Jan
Mike Nov
Song Sept
Ted Feb
Yuki Aug

2. 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

3. 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
Cong 19446
John 19446
Kate 19446
Song 19446
Yuki 19446

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

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

6. 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}