Lecture 7 CSE 331 Sep 15, 2010

Reminder I will not accept HWs after 1:15pm HW 1 is due Friday Prelim grading rubric up on the blog I will not accept HWs after 1:15pm

HW 0 solutions posted Use them as model solutions for your future HWs

Pre-emptive apology icanhascheezburger.com

Return signed forms I’ll need confirmation in writing. No graded material will be handed back till I get this signed form from you!

Gale-Shapley Algorithm Intially all men and women are free While there exists a free woman who can propose Let w be such a woman and m be the best man she has not proposed to w proposes to m If m is free (m,w) get engaged Else (m,w’) are engaged If m prefers w’ to w w remains free Else (m,w) get engaged and w’ is free Output the engaged pairs as the final output

Preferences

GS algorithm: Firefly Edition 1 2 3 4 5 6 1

Denise’s Q Why not choose a free woman more smartly?

Today’s lecture At most n2 iterations of the while loop GS algorithms always outputs a stable marriage