Yi-Shin Chen and Cyrus shahabi f i igure n, whe 10 represents complete chaos. The X-axis is the number of generations and the Y-axis depicts the similarity distance(between query results and perfect. user feedback) computed by Equation(10). As revealed by i igure n, although the noise levels affect the of result mecha 20% ure indicates that g mechanism has the ability to tolerate 6 Concision dation system to reduce the information overload problem in e-commerce. However, this sy stem heavily relies on user prol les for providing accurate recommendation lists. The system accuracy may decline if user prolles are inaccurate. Therefore, we introduced a learning mechanism that utilizes the users navigation behaviors to improve the prol les automat ng genetic algorithms. The experimental results indicated that the accuracy of results signil cantly increased up to 100% by our GA-based learn- g mechanism. It also demonstrated that our learning mechanism has the ability of tolerating noises during learning processes and improvement is in he range of 20% to 50% depending on the noise level RP3PrPncP fi Shahabi C, d anaei-Kashani F, Chen Y -S, McLeod D, (200fi) Yoda: An Accu rate and Scalable Web-based Recommendation System. In croceedings of Sixth nternational Conference on Cooperative Information Systems(CoopIS 200f 2. Moukas A,( f996)Amalthea: Information discovery and filtering using a mul tiagent evolving ecosystem. In croceedings of fist Int. Conf. on The c ractical Applications of Intelligent Agents and Multi Agent Technology(c AAM) n. Sheth d, (f99n) Evolving Agents for cersonalized Information Filtering In cro ence on ar icial Intelligence for Applications 4. Holland J.,(p: 5)Adaption in Natural and Artificial Systems. University of Michigan cress. Ann Arbor. Michigan 5. Konstan J, Miller d, Maltz D, Herlocker J, Gordon L, Riedl J., (f99: )Ap- lying collaborative Filtering to Usenet News. In: Communications of the ACM 6. Shahabi C, Zarkesh A M, Adibi J, Shah., (699: Knowledge Discovery from Users Web cage Navigation. In croceedings of the IEEE RIDE9: Workshop Sarwar d, Karypis G, Konstan J, Riedl J(2000) Application of Dimensionality Reduction in Recommender System 5 A Case Study. In croceedings of ACM WebKDD 2000 Web Mining for e-Commerce Workshop 8. Kitts d, Freed D.,. rieze M,(2000)Cross-sell, a fast promotion-tunable customer-iten recommendation method based on conditionally independent ence on Knowledge discovery and data mining, pp 4n-s nternational confer- probabilities. In croceedings of the sixth ACM SIGKDD￾✽❼ ➳✸❵ ❸❡❜✦✇♥❵❚①❤✕✇♥❳✽❚✵❬✍❚❉❪①❤✈❝✦❩❇♠♥❞❍❜✦✇❉❬✍✇❉❬✍➝♥❵ ➱✦❮◗❃✕❃Ð❛❖❊◆P■ ❚❊❐✂ç✱❈❊■✍◆P■①❋❊➱❛❃④◗❭■①Ï■✍Ò❛■✍Ï✎❭✝◆P■✍ß❊◆P■❦◗❭■✍❋♥❒✽◗➽ß➩■✍◆❭❮➊■❦➮❫❒✛❮➊■✍■❦❑⑧❘▲❏❛➮✽Óá❏✦❋▲❑á❋❊➱❛❃④◗❭■①Ï■✍Ò❛■✍Ï ✱✶❭➢◆P■✍ß❊◆P■❦◗❭■✍❋♥❒✽◗❄➮✣➱❛✃✵ß❊Ï■✣❒P■✵➮✽❈▲❏✦➱♥◗✍ä➤æ✸❈❊■ ✆✖❅q❏❲é⑧❃④◗✡❃④◗✡❒P❈❊■✵❋❉❖❊✃✧❘➩■✍◆➽➱✦❮❍Ð❛■✍❋❊■✍◆✽❏❲❒P❃➱❛❋▲◗✡❏✦❋▲❑ ❒P❈❊■❄❂✡❅q❏❲é⑧❃④◗✐❑⑧■✍ß❊❃④➮❫❒✽◗❍❒P❈❊■❣◗❭❃✃✵❃ Ï④❏✦◆P❃❒❇▼①❑⑧❃④◗❇❒✽❏✦❋▲➮✣■❂✜➊❘➩■✣❒❇ç✐■✍■✍❋☞Ñ♥❖❊■✍◆P▼①◆P■❦◗❭❖❊Ï❒✽◗✸❏✦❋▲❑➢ß➩■✍◆❭❮➊■❦➮❫❒ ❖▲◗❭■✍◆✈❮➊■✍■❦❑⑧❘▲❏❛➮✽Ó❋✣✈➮✣➱❛✃✵ß❊❖⑧❒P■❦❑✛❘❉▼ ✟❍Ñ♥❖▲❏❲❒P❃➱❛❋ ✜ ✱✶❭ ✣❫ä Þ◗✕◆P■✍Ò❛■❦❏✦Ï■❦❑❣❘❉▼✰❃✕❃Ð❛❖❊◆P■ ❚❊❐❲❏✦Ï❒P❈❊➱❛❖❊Ð❛❈ ❒P❈❊■➢❋❊➱❛❃④◗❭■➢Ï■✍Ò❛■✍Ï④◗✛❏❲â➤■❦➮❫❒✛❒P❈❊■☞❏❛➮✍➮✣❖❊◆✽❏❛➮✣▼å➱✦❮✱◆P■❦◗❭❖❊Ï❒✽◗✍❐✈➱❛❖❊◆✛Ï■❦❏✦◆P❋❊❃❋❊Ð✿✃✵■❦➮✽❈▲❏✦❋❊❃④◗❭✃ ◗❇❒P❃ Ï Ï ❃✃✵ß❊◆P➱❲Ò❛■❦◗❄❒P❈❊■➧Ñ♥❖▲❏✦Ï ❃❒❇▼✢➱✦❮✱❖▲◗❭■✍◆✛ß❊◆P➱✥￾▲Ï■❦◗❣❃❋ ❒P❈❊■➢◆✽❏✦❋❊Ð❛■✵➱✦❮✢✷✥❭✄ ❒P➱ ✁ ❭✄ ä✈æ✸❈❊❃④◗✰￾▲Ð✦❅ ❖❊◆P■✧❃❋▲❑⑧❃④➮✍❏❲❒P■❦◗✡❒P❈▲❏❲❒❄➱❛❖❊◆❄Ï■❦❏✦◆P❋❊❃❋❊Ð➧✃✵■❦➮✽❈▲❏✦❋❊❃④◗❭✃ ❈▲❏❛◗✖❒P❈❊■✮❏✦❘❊❃ Ï ❃❒❇▼✝❒P➱➢❒P➱❛Ï■✍◆✽❏❲❒P■✧❋❊➱❛❃④◗❭■❦◗ ❑⑧❖❊◆P❃❋❊Ð✮❒P❈❊■❣Ï■❦❏✦◆P❋❊❃❋❊Ð✵ß❊◆P➱⑧➮✣■❦◗P◗✍ä ￾ ✁áÙ❍Ö✡Ü ✠❭Û✎✏❉Ý❇Ù❍Ö ûá■✵ß❊◆P➱❛ß➩➱♥◗❭■❦❑å❏☞◆P■❦➮✣➱❛✃✵✃✵■✍❋▲❑❊❏❲❒P❃➱❛❋✢◗❭▼⑧◗❇❒P■✍✃ ❒P➱✝◆P■❦❑⑧❖▲➮✣■✧❒P❈❊■✵❃❋⑧❮➊➱❛◆P✃①❏❲❒P❃➱❛❋å➱❲Ò❛■✍◆PÏ➱♥❏❛❑ ß❊◆P➱❛❘❊Ï■✍✃ ❃❋❣■✣❅q➮✣➱❛✃✵✃✵■✍◆✽➮✣■❛ä✟✦✖➱❲ç✐■✍Ò❛■✍◆❦❐✽❒P❈❊❃④◗✂◗❭▼⑧◗❇❒P■✍✃ ❈❊■❦❏tÒ❉❃ Ï▼✖◆P■✍Ï ❃■❦◗❁➱❛❋➽❖▲◗❭■✍◆✂ß❊◆P➱✥￾▲Ï■❦◗➩❮➊➱❛◆ ß❊◆P➱❲Ò❉❃④❑⑧❃❋❊Ð❄❏❛➮✍➮✣❖❊◆✽❏❲❒P■❍◆P■❦➮✣➱❛✃✵✃✵■✍❋▲❑❊❏❲❒P❃➱❛❋✧Ï ❃④◗❇❒✽◗✍ä❲æ✸❈❊■✱◗❭▼⑧◗❇❒P■✍✃ ❏❛➮✍➮✣❖❊◆✽❏❛➮✣▼➽✃①❏t▼✛❑⑧■❦➮✣Ï ❃❋❊■✐❃❮ ❖▲◗❭■✍◆✡ß❊◆P➱✥￾▲Ï■❦◗✖❏✦◆P■❣❃❋▲❏❛➮✍➮✣❖❊◆✽❏❲❒P■❛ä▲æ✸❈❊■✍◆P■✣❮➊➱❛◆P■❛❐❊ç✐■✛❃❋♥❒P◆P➱⑧❑⑧❖▲➮✣■❦❑✿❏✵Ï■❦❏✦◆P❋❊❃❋❊Ð①✃✵■❦➮✽❈▲❏✦❋❊❃④◗❭✃ ❒P❈▲❏❲❒✐❖⑧❒P❃ Ï ❃❰✍■❦◗✼❒P❈❊■✡❖▲◗❭■✍◆✽◗✍ü❛❋▲❏tÒ❉❃Ð♥❏❲❒P❃➱❛❋✮❘➩■✍❈▲❏tÒ❉❃➱❛◆✽◗②❒P➱✧❃✃✵ß❊◆P➱❲Ò❛■✸❒P❈❊■✡ß❊◆P➱✥￾▲Ï■❦◗❍❏✦❖⑧❒P➱❛✃①❏❲❒❭❅ ❃④➮✍❏✦Ï Ï▼✝❖▲◗❭❃❋❊Ð➧Ð❛■✍❋❊■✣❒P❃④➮✧❏✦ÏÐ❛➱❛◆P❃❒P❈❊✃①◗✍ä➤æ✸❈❊■✧■✣é⑧ß➩■✍◆P❃✃✵■✍❋♥❒✽❏✦Ï✕◆P■❦◗❭❖❊Ï❒✽◗✡❃❋▲❑⑧❃④➮✍❏❲❒P■❦❑✿❒P❈▲❏❲❒❄❒P❈❊■ ❏❛➮✍➮✣❖❊◆✽❏❛➮✣▼➽➱✦❮➩◆P■❦◗❭❖❊Ï❒✽◗✟◗❭❃Ð❛❋❊❃￾➩➮✍❏✦❋♥❒PÏ▼❣❃❋▲➮✣◆P■❦❏❛◗❭■❦❑✛❖❊ß✧❒P➱❂✱✶❭❉❭✄ ❘❉▼✛➱❛❖❊◆✑✮Þ❅❡❘▲❏❛◗❭■❦❑✧Ï■❦❏✦◆P❋⑧❅ ❃❋❊Ð✿✃✵■❦➮✽❈▲❏✦❋❊❃④◗❭✃✝ä✈è❡❒✮❏✦Ï④◗❭➱✿❑⑧■✍✃✵➱❛❋▲◗❇❒P◆✽❏❲❒P■❦❑✢❒P❈▲❏❲❒✧➱❛❖❊◆✛Ï■❦❏✦◆P❋❊❃❋❊Ð✝✃✵■❦➮✽❈▲❏✦❋❊❃④◗❭✃✻❈▲❏❛◗❣❒P❈❊■ ❏✦❘❊❃ Ï ❃❒❇▼✿➱✦❮❍❒P➱❛Ï■✍◆✽❏❲❒P❃❋❊Ð➧❋❊➱❛❃④◗❭■❦◗➽❑⑧❖❊◆P❃❋❊Ð☞Ï■❦❏✦◆P❋❊❃❋❊Ð➧ß❊◆P➱⑧➮✣■❦◗P◗❭■❦◗❄❏✦❋▲❑å❃✃✵ß❊◆P➱❲Ò❛■✍✃✵■✍❋♥❒❄❃④◗➽❃❋ ❒P❈❊■❣◆✽❏✦❋❊Ð❛■❄➱✦❮✑✷✥❭✄ ❒P➱ ✁ ❭✄ ❑⑧■✍ß➩■✍❋▲❑⑧❃❋❊Ð①➱❛❋➧❒P❈❊■❣❋❊➱❛❃④◗❭■➽Ï■✍Ò❛■✍Ï❯ä ✂☎✂☎✂Ø✌☎✈Ö✡Ü☎ ✏ ￾❦➟✖❜✦✇❉❬✍✇❉❬✍➝♥❵⑧❤❍➟ ⑤ ✌②❬✍❚❉❬✍❳✽❵ ❸☎✄✖❬✍❞q✇❉❬✍❚♥❵⑧ÿ✕➟ ⑤✦❤✕✇♥❳✽❚➽➳❄➟ ❸❡❜⑧➟ ⑤❲❴✮♦❫⑥▲❳✽❥✦❪❣♣❄➟ ⑤♥➸❾❹✍❶❦❶✁￾✣➻❁➳✕❥✦❪♥❬✦❿❲⑦❍❚❣⑦❍♦✽♦✽♠❛❸ ❩❭❬✣❱❇❳✱❬✍❚❉❪✧❜✦♦❫❬✍③ ❬✍➝♥③ ❳✝✆✝❳✽➝❛❸❾➝❉❬✍❞q❳❫❪ ➛❳✽♦✽❥❦❢❣❢❣❳✽❚❉❪♥❬✣❱❇❵❥❦❚✧❜❲❝❛❞❡❱❇❳✽❢✵➟❲❙❯❚ ☎❩❇❥❲♦✽❳✽❳❫❪❛❵❚♥❨❦❞✼❥✍✉✂❜✦❵➲✦❱❇✇ ❙❯❚❲❱❇❳P❩❇❚❉❬✣❱❇❵❥❦❚❉❬✍③➤❤✕❥❦❚❛✉④❳P❩❇❳✽❚♥♦✽❳✖❥❦❚➢❤✕❥❲❥❦❧⑧❳P❩❭❬✣❱❇❵st❳✖❙❯❚❛✉④❥✍❩❇❢✛❬✣❱❇❵❥❦❚①❜❲❝❛❞❡❱❇❳✽❢❣❞✱➸❾❤✕❥❲❥❦❧♥❙q❜✵❹✍❶❦❶✁￾✣➻ ❹❲➟✖❴✮❥❦♠♥➞❦❬✍❞✖⑦✖➟ ⑤✂➸✍￾❫⑨❦⑨❦❻t➻✸⑦❍❢✛❬✍③❱❇✇♥❳❫❬✦❿❊❙❯❚❛✉④❥✍❩❇❢✛❬✣❱❇❵❥❦❚☞❪❛❵ ❞q♦✽❥✣st❳P❩q❝➧❬✍❚❉❪①➦❉③❱❇❳P❩❇❵❚♥❨✧♠♥❞q❵❚♥❨✵❬✛❢❄♠♥③ ❸ ❱❇❵ ❬✍❨❦❳✽❚❲❱➽❳✽st❥❦③s✦❵❚♥❨①❳✽♦✽❥❦❞❡❝❛❞❡❱❇❳✽❢✵➟➤❙❯❚ ☎❩❇❥❲♦✽❳✽❳❫❪❛❵❚♥❨❦❞❄❥✍✉ ￾✽❞❡❱➽❙❯❚❲❱❫➟❁❤✕❥❦❚❛✉❯➟✂❥❦❚å➠②✇♥❳ ☎❩❭❬✍♦P❱❇❵ ♦❫❬✍③ ⑦❍❧♥❧♥③ ❵ ♦❫❬✣❱❇❵❥❦❚♥❞❍❥✍✉❁❙❯❚❲❱❇❳✽③ ③ ❵❨❦❳✽❚❲❱✐⑦❍❨❦❳✽❚❲❱❇❞✼❬✍❚❉❪①❴✮♠♥③❱❇❵⑦❍❨❦❳✽❚❲❱❍➠➩❳✽♦❭✇♥❚♥❥❦③❥❦❨✍❝☞➸ ☎⑦✐⑦✸❴①➻ ✝✦➟✖❜✦✇♥❳P❱❇✇ ✌❍➟ ⑤♥➸✍￾❫⑨❦⑨ ✝t➻❁❽✂st❥❦③s✦❵❚♥❨✱⑦❍❨❦❳✽❚❲❱❇❞➤✉④❥✍❩ ☎❳P❩❇❞q❥❦❚❉❬✍③ ❵ ➵✽❳❫❪➽❙❯❚❛✉④❥✍❩❇❢✛❬✣❱❇❵❥❦❚➽ÿ➤❵ ③ ❱❇❳P❩❇❵❚♥❨❛➟t❙❯❚ ☎❩❇❥✍❸ ♦✽❳✽❳❫❪❛❵❚♥❨❦❞✂❥✍✉❉❱❇✇♥❳②þ✐❵❚❲❱❇✇✡❙❡❽✈❽✈❽☞❤✕❥❦❚❛✉④❳P❩❇❳✽❚♥♦✽❳✼❥❦❚➽⑦✼❩q❱❇❵➦❉♦✽❵ ❬✍③✦❙❯❚❲❱❇❳✽③ ③ ❵❨❦❳✽❚♥♦✽❳②✉④❥✍❩✕⑦❍❧♥❧♥③ ❵ ♦❫❬✣❱❇❵❥❦❚♥❞ ❼❛➟✸➨✐❥❦③ ③ ❬✍❚❉❪✟✞❛➟ ⑤✐➸✍￾❫⑨✄✂❦❺❦➻❣⑦✐❪♥❬✍❧❛❱❇❵❥❦❚✢❵❚áþ✸❬✣❱❇♠❛❩❭❬✍③✐❬✍❚❉❪✢⑦✼❩q❱❇❵➦❉♦✽❵ ❬✍③✸❜❲❝❛❞❡❱❇❳✽❢❣❞✽➟✂r✐❚♥❵st❳P❩❇❞q❵❱❯❝å❥✍✉ ❴✮❵ ♦❭✇♥❵❨t❬✍❚ ☎❩❇❳✽❞q❞✽⑤⑧⑦❍❚♥❚✵⑦✼❩❇➝⑧❥✍❩❫⑤❉❴✮❵ ♦❭✇♥❵❨t❬✍❚ ❺❲➟✝✄✱❥❦❚♥❞❡❱❭❬✍❚✠✞❛➟ ⑤➤❴✮❵ ③ ③ ❳P❩ ✌❍➟ ⑤➩❴✵❬✍③❱❇➵❄♣❄➟ ⑤❊➨✐❳P❩❇③❥❲♦❭➞t❳P❩✡✞❛➟ ⑤➩➺✐❥✍❩❭❪❛❥❦❚☞⑥✂➟ ⑤ ➛❵ ❳❫❪❛③☛✞❛➟ ⑤✂➸✍￾❫⑨❦⑨✄✂❦➻✸⑦❍❧❛❸ ❧♥③❝❛❵❚♥❨✡❤✕❥❦③ ③ ❬✍➝⑧❥✍❩❭❬✣❱❇❵st❳✸ÿ➤❵ ③❱❇❳P❩❇❵❚♥❨✱❱❇❥✱r✐❞q❳✽❚♥❳P❱✈þ✐❳P➜✼❞✽➟❲❙❯❚▲❿❲❤✕❥❦❢❣❢❄♠♥❚♥❵ ♦❫❬✣❱❇❵❥❦❚♥❞✈❥✍✉⑧❱❇✇♥❳❍⑦❍❤✟❴ ➸➀❼t❶t➻ ✝ ❻✦➟✖❜✦✇❉❬✍✇❉❬✍➝♥❵❊❤❍➟ ⑤✌☞❊❬✣❩❇➞t❳✽❞q✇✛⑦✖➟ ❴➧➟ ⑤❛⑦✐❪❛❵➝♥❵✍✞❛➟ ⑤❛❜✦✇❉❬✍✇✏✎✡➟ ⑤⑧➸✍￾❫⑨❦⑨✄✂❦➻✑✄✱❚♥❥❫➜✼③ ❳❫❪❛❨❦❳❍♣✸❵ ❞q♦✽❥✣st❳P❩q❝➽✉❩❇❥❦❢ r✐❞q❳P❩❇❞✒✆✝❳✽➝ ☎❬✍❨❦❳✖þ✸❬❫s✦❵❨t❬✣❱❇❵❥❦❚▲➟❉❙❯❚ ☎❩❇❥❲♦✽❳✽❳❫❪❛❵❚♥❨❦❞❍❥✍✉➤❱❇✇♥❳✱❙❡❽✈❽✈❽ ➛❙❯♣✱❽✈⑨✄✂✡✆✝❥✍❩❇➞✦❞q✇♥❥❦❧ ✂❲➟✖❜❛❬✣❩q➜✟❬✣❩ ✌❍➟ ⑤✓✄✖❬✣❩q❝❛❧♥❵ ❞❁➺✡➟ ⑤✓✄✱❥❦❚♥❞❡❱❭❬✍❚✔✞❛➟ ⑤ ➛❵ ❳❫❪❛③✕✞❛➟✦➸❾❹✍❶❦❶❦❶t➻➩⑦❍❧♥❧♥③ ❵ ♦❫❬✣❱❇❵❥❦❚✖❥✍✉♥♣✸❵❢❣❳✽❚♥❞q❵❥❦❚❉❬✍③ ❵ ❱❯❝ ➛❳❫❪❛♠♥♦P❱❇❵❥❦❚✿❵❚ ➛❳✽♦✽❥❦❢❣❢❣❳✽❚❉❪❛❳P❩❄❜❲❝❛❞❡❱❇❳✽❢✗✖✝⑦ ❤②❬✍❞q❳①❜❲❱❇♠❉❪✦❝❲➟➩❙❯❚ ☎❩❇❥❲♦✽❳✽❳❫❪❛❵❚♥❨❦❞➽❥✍✉✸⑦❍❤✟❴ ✆✝❳✽➝✌✄✱♣✸♣✫❹✍❶❦❶❦❶✘✆✝❳✽➝①❴✮❵❚♥❵❚♥❨➽✉④❥✍❩❍❳P❸❡❤✕❥❦❢❣❢❣❳P❩❇♦✽❳✙✆✝❥✍❩❇➞✦❞q✇♥❥❦❧ ❷✦➟✝✄✱❵❱q❱❇❞ ✌❍➟ ⑤①ÿ❛❩❇❳✽❳❫❪✙♣❄➟ ⑤✚✎✂❩❇❵ ❳✽➵✽❳ ❴➧➟ ⑤✝➸❾❹✍❶❦❶❦❶t➻q❤✈❩❇❥❦❞q❞❡❸❾❞q❳✽③ ③➀⑤➧❬ ✉➀❬✍❞❡❱ö❧❛❩❇❥❦❢❣❥✍❱❇❵❥❦❚❛❸➊❱❇♠♥❚❉❬✍➝♥③ ❳ ♦✽♠♥❞❡❱❇❥❦❢❣❳P❩q❸❾❵❱❇❳✽❢✳❩❇❳✽♦✽❥❦❢❣❢❣❳✽❚❉❪♥❬✣❱❇❵❥❦❚✫❢❣❳P❱❇✇♥❥✦❪✫➝❉❬✍❞q❳❫❪ ❥❦❚ ♦✽❥❦❚❉❪❛❵❱❇❵❥❦❚❉❬✍③ ③❝ ❵❚❉❪❛❳✽❧⑧❳✽❚❉❪❛❳✽❚❲❱ ❧❛❩❇❥❦➝❉❬✍➝♥❵ ③ ❵❱❇❵ ❳✽❞✽➟❁❙❯❚ ☎❩❇❥❲♦✽❳✽❳❫❪❛❵❚♥❨❦❞✡❥✍✉✟❱❇✇♥❳➽❞q❵➲✦❱❇✇✝⑦❍❤✟❴✩❜✦❙q➺✙✄✱♣✸♣ ❵❚❲❱❇❳P❩❇❚❉❬✣❱❇❵❥❦❚❉❬✍③✈♦✽❥❦❚❛✉④❳P❩q❸ ❳✽❚♥♦✽❳✱❥❦❚✛✄✱❚♥❥❫➜✼③ ❳❫❪❛❨❦❳✖❪❛❵ ❞q♦✽❥✣st❳P❩q❝✮❬✍❚❉❪✵❪♥❬✣❱❭❬❄❢❣❵❚♥❵❚♥❨❛⑤❛❧♥❧▲➟❛❼✄✝✄✂❫❸❾❼❦❼t❻