Improving User 1 rofiles for E-Commerce by Genetic Algorithms 9 4.3 hhse IIi -Adjusaiy o User Seaaiy o s This learning mechanism is a background process performed at the same time that the users navigate the web-site. It employs ga for improving the list of confidence values by decoding the best chromosome to replace existing one n the system after its evolution. Users are not required to make additional effort to improve these confidence values. Yoda collects users'follow-up nav gation behaviors and employs these behaviors as the goal of ga prior to the beginning of evolution Note that the learning mechanism is only triggered ation data. In plementation, it is activated when the number of navigated items is the same as that of the recommended hod for transforming the navigation data to the relevance feedback needed in GA. 1 et(n be the set of follow -up navigated items and i be an item in( N. As described in Section 4.1, Yoda can capture the view-time, the hit-count and sequence about the items. Therefore, (M (N={(i,vt(),v3(1),Uh():(r,v( Us(i): sequence of i in reverse order, vh(i): hit-count of iB Assuming that users only navigate potentially desired items, the prefer ences of items Can be estimated from navigation behaviors. That is, the users re more interested in the items that are navigated earlier, accesses more of ten, or viewed for longer periods of time. As a result, the feedback preference Tu(i)of the navigated item i from user u's perspective could be estimated ased on the navigation data by using Equation( 9 he ght of feature f f: the mean of navigation data in feature f cation d if f(i)< ifv(i)>(f+ n()=(us×vs)×(ah×th)×(ut×v) Note that for the normalization purpose, we use(f+n x of)as the upper bound in Equation(t). This upper bound can prevent the affect from Note that Ga would converge per evolution process and there is no guarantee that❙❯❢❣❧❛❩❇❥✣s✦❵❚♥❨✡r✐❞q❳P❩ ☎❩❇❥✍➦❉③ ❳✽❞✟✉④❥✍❩✸❽❁❸❡❤✕❥❦❢❣❢❣❳P❩❇♦✽❳✸➝❲❝✮➺✐❳✽❚♥❳P❱❇❵ ♦✖⑦❍③❨❦❥✍❩❇❵❱❇✇♥❢❣❞ ⑨ ✍✏✎ ✫ ✓✖✕❈❊➷❦➚✘✗✆✗✆✗ ✙✁￾➧➴✄✂✴✢✕➷✄❏✶❍✪▼✢✜✤✣☞➷❦➚♥➘✆☎✂➚❏✄❏✶❍✪▼✢✜➩➷ æ✸❈❊❃④◗✕Ï■❦❏✦◆P❋❊❃❋❊Ð✡✃✵■❦➮✽❈▲❏✦❋❊❃④◗❭✃ ❃④◗✕❏✡❘▲❏❛➮✽Ó❉Ð❛◆P➱❛❖❊❋▲❑➽ß❊◆P➱⑧➮✣■❦◗P◗✈ß➩■✍◆❭❮➊➱❛◆P✃✵■❦❑✧❏❲❒✈❒P❈❊■✱◗P❏✦✃✵■✼❒P❃✃✵■ ❒P❈▲❏❲❒✐❒P❈❊■➽❖▲◗❭■✍◆✽◗❍❋▲❏tÒ❉❃Ð♥❏❲❒P■✖❒P❈❊■❄ç✐■✍❘⑧❅q◗❭❃❒P■❛ä❉è❡❒✱■✍✃✵ß❊Ï➱❲▼⑧◗ ✮Þ ❮➊➱❛◆✐❃✃✵ß❊◆P➱❲Ò❉❃❋❊Ð✛❒P❈❊■➽Ï ❃④◗❇❒✸➱✦❮ ➮✣➱❛❋❆￾➩❑⑧■✍❋▲➮✣■✵Ò❲❏✦Ï❖❊■❦◗❄❘❉▼✢❑⑧■❦➮✣➱⑧❑⑧❃❋❊Ð➧❒P❈❊■✵❘➩■❦◗❇❒✧➮✽❈❊◆P➱❛✃✵➱♥◗❭➱❛✃✵■❣❒P➱✝◆P■✍ß❊Ï④❏❛➮✣■✮■✣é⑧❃④◗❇❒P❃❋❊Ð☞➱❛❋❊■ ❃❋å❒P❈❊■✵◗❭▼⑧◗❇❒P■✍✃✘❏❲❮➀❒P■✍◆❄❃❒✽◗❄■✍Ò❛➱❛Ï❖⑧❒P❃➱❛❋✂ä ✧✡◗❭■✍◆✽◗❄❏✦◆P■✛❋❊➱✦❒➽◆P■❦Ñ♥❖❊❃ ◆P■❦❑☞❒P➱☞✃①❏✦Ó❛■✧❏❛❑❊❑⑧❃❒P❃➱❛❋▲❏✦Ï ■✣â➤➱❛◆❭❒✐❒P➱✵❃✃✵ß❊◆P➱❲Ò❛■✖❒P❈❊■❦◗❭■➽➮✣➱❛❋❆￾➩❑⑧■✍❋▲➮✣■❄Ò❲❏✦Ï❖❊■❦◗✍ä♥❂✼➱⑧❑❊❏✵➮✣➱❛Ï Ï■❦➮❫❒✽◗✐❖▲◗❭■✍◆✽◗✍ü❛❮➊➱❛Ï Ï➱❲ç✸❅❡❖❊ß➧❋▲❏tÒ♥❅ ❃Ð♥❏❲❒P❃➱❛❋①❘➩■✍❈▲❏tÒ❉❃➱❛◆✽◗✼❏✦❋▲❑✵■✍✃✵ß❊Ï➱❲▼⑧◗✟❒P❈❊■❦◗❭■✖❘➩■✍❈▲❏tÒ❉❃➱❛◆✽◗✼❏❛◗✟❒P❈❊■✡Ð❛➱♥❏✦Ï❊➱✦❮ ✮Þ ß❊◆P❃➱❛◆✟❒P➱✛❒P❈❊■ ❘➩■✍Ð❛❃❋❊❋❊❃❋❊Ð➢➱✦❮②■✍Ò❛➱❛Ï❖⑧❒P❃➱❛❋✞✝✦ä ✝✖➱✦❒P■❣❒P❈▲❏❲❒✖❒P❈❊■✛Ï■❦❏✦◆P❋❊❃❋❊Ð①✃✵■❦➮✽❈▲❏✦❋❊❃④◗❭✃ ❃④◗✱➱❛❋❊Ï▼➢❒P◆P❃Ð❛Ð❛■✍◆P■❦❑ ❏❲❮➀❒P■✍◆✟◆P■❦➮✣■✍❃Ò❉❃❋❊Ð➽■✍❋❊➱❛❖❊Ð❛❈✮❋▲❏tÒ❉❃Ð♥❏❲❒P❃➱❛❋✮❑❊❏❲❒✽❏❊ä❲èq❋✵➱❛❖❊◆✟❃✃✵ß❊Ï■✍✃✵■✍❋♥❒✽❏❲❒P❃➱❛❋✂❐✦❃❒✼❃④◗✼❏❛➮❫❒P❃Ò❲❏❲❒P■❦❑ ç✱❈❊■✍❋✵❒P❈❊■✡❋❉❖❊✃✧❘➩■✍◆❍➱✦❮❁❋▲❏tÒ❉❃Ð♥❏❲❒P■❦❑✮❃❒P■✍✃①◗✼❃④◗✟❒P❈❊■✡◗P❏✦✃✵■✡❏❛◗②❒P❈▲❏❲❒✐➱✦❮➤❒P❈❊■✖◆P■❦➮✣➱❛✃✵✃✵■✍❋▲❑⑧■❦❑ ❃❒P■✍✃①◗✱❃❋☞❒P❈❊■❣ç✱❃④◗❭❈⑧❅❡Ï ❃④◗❇❒❦ä ûá■✢￾▲◆✽◗❇❒✱❑⑧■❦◗P➮✣◆P❃❘➩■✡❒P❈❊■➽✃✵■✣❒P❈❊➱⑧❑①❮➊➱❛◆✐❒P◆✽❏✦❋▲◗❇❮➊➱❛◆P✃✵❃❋❊Ð✛❒P❈❊■❄❋▲❏tÒ❉❃Ð♥❏❲❒P❃➱❛❋➧❑❊❏❲❒✽❏❣❒P➱✮❒P❈❊■ ◆P■✍Ï■✍Ò❲❏✦❋▲➮✣■❄❮➊■✍■❦❑⑧❘▲❏❛➮✽Ó➧❋❊■✍■❦❑⑧■❦❑☞❃❋ ✮Þ ä ✱✂■✣❒ ✜✘✓❘➩■❣❒P❈❊■✛◗❭■✣❒✡➱✦❮✕❮➊➱❛Ï Ï➱❲ç✸❅❡❖❊ß☞❋▲❏tÒ❉❃Ð♥❏❲❒P■❦❑ ❃❒P■✍✃①◗❍❏✦❋▲❑ ✔✕❘➩■✡❏✦❋①❃❒P■✍✃➫❃❋ ✜✘àä Þ◗❍❑⑧■❦◗P➮✣◆P❃❘➩■❦❑✵❃❋➧❆❉■❦➮❫❒P❃➱❛❋❲✲▲ä ✱❛❐❲❂✼➱⑧❑❊❏✛➮✍❏✦❋①➮✍❏✦ß⑧❒P❖❊◆P■ ❒P❈❊■①Ò❉❃■✍ç✸❅❯❒P❃✃✵■❛❐➤❒P❈❊■✵❈❊❃❒❭❅q➮✣➱❛❖❊❋♥❒✛❏✦❋▲❑á◗❭■❦Ñ♥❖❊■✍❋▲➮✣■①❏✦❘➩➱❛❖⑧❒➽❒P❈❊■①❃❒P■✍✃①◗✍ä✂æ✸❈❊■✍◆P■✣❮➊➱❛◆P■❛❐ ✜✘ ➮✍❏✦❋☞❘➩■➽❮➊➱❛◆P✃①❏✦Ï Ï▼➧❑⑧■✟￾▲❋❊■❦❑✝❏❛◗✄✂ ✜✘☛✏ ✒✙✜ ✔✌✔✠✟☛✡✓✜ ✔ ✣ ✔✠✟✞☞✤✜ ✔ ✣ ✔✠✟■ ✜ ✔ ✣ ✣ ✖ ✔✎✂ ✜ ✍ ✔✠✟☛✡✓✜ ✔ ✣❄✂✦Ò❉❃■✍ç✸❅❯❒P❃✃✵■➽➱✦❮✩✔✌✔ ✟✞☞✤✜ ✔ ✣❄✂❛◗❭■❦Ñ♥❖❊■✍❋▲➮✣■➽➱✦❮✩✔✼❃❋✝◆P■✍Ò❛■✍◆✽◗❭■❄➱❛◆✽❑⑧■✍◆✣✔✠✟■ ✜ ✔ ✣❄✂✦❈❊❃❒❭❅q➮✣➱❛❖❊❋♥❒✖➱✦❮ ✔ ✘ ✜ ❪✥✣ Þ◗P◗❭❖❊✃✵❃❋❊Ð➢❒P❈▲❏❲❒➽❖▲◗❭■✍◆✽◗✡➱❛❋❊Ï▼✿❋▲❏tÒ❉❃Ð♥❏❲❒P■✛ß➩➱✦❒P■✍❋♥❒P❃④❏✦Ï Ï▼å❑⑧■❦◗❭❃ ◆P■❦❑✿❃❒P■✍✃①◗✍❐➤❒P❈❊■✮ß❊◆P■✣❮➊■✍◆❭❅ ■✍❋▲➮✣■❦◗✟➱✦❮❁❃❒P■✍✃①◗✼➮✍❏✦❋①❘➩■✱■❦◗❇❒P❃✃①❏❲❒P■❦❑✮❮➊◆P➱❛✃✙❋▲❏tÒ❉❃Ð♥❏❲❒P❃➱❛❋✮❘➩■✍❈▲❏tÒ❉❃➱❛◆✽◗✍ä✦æ✸❈▲❏❲❒✼❃④◗✍❐✦❒P❈❊■✖❖▲◗❭■✍◆✽◗ ❏✦◆P■✡✃✵➱❛◆P■❄❃❋♥❒P■✍◆P■❦◗❇❒P■❦❑①❃❋➧❒P❈❊■❄❃❒P■✍✃①◗✐❒P❈▲❏❲❒✱❏✦◆P■❄❋▲❏tÒ❉❃Ð♥❏❲❒P■❦❑✵■❦❏✦◆PÏ ❃■✍◆❦❐❉❏❛➮✍➮✣■❦◗P◗❭■❦◗❍✃✵➱❛◆P■✡➱✦❮➀❅ ❒P■✍❋✂❐♥➱❛◆✼Ò❉❃■✍ç✐■❦❑✧❮➊➱❛◆❍Ï➱❛❋❊Ð❛■✍◆✼ß➩■✍◆P❃➱⑧❑❊◗✟➱✦❮➤❒P❃✃✵■❛ä Þ◗❍❏❣◆P■❦◗❭❖❊Ï❒❦❐✦❒P❈❊■✱❮➊■✍■❦❑⑧❘▲❏❛➮✽Ó✮ß❊◆P■✣❮➊■✍◆P■✍❋▲➮✣■ ✥✌✛✴✜ ✔ ✣➽➱✦❮✸❒P❈❊■➢❋▲❏tÒ❉❃Ð♥❏❲❒P■❦❑✢❃❒P■✍✃ ✔✖❮➊◆P➱❛✃✓❖▲◗❭■✍◆ ✙✕ü ◗❣ß➩■✍◆✽◗❭ß➩■❦➮❫❒P❃Ò❛■➧➮✣➱❛❖❊Ï④❑ ❘➩■➢■❦◗❇❒P❃✃①❏❲❒P■❦❑ ❘▲❏❛◗❭■❦❑➧➱❛❋➧❒P❈❊■❣❋▲❏tÒ❉❃Ð♥❏❲❒P❃➱❛❋☞❑❊❏❲❒✽❏✮❘❉▼➧❖▲◗❭❃❋❊Ð ✟❍Ñ♥❖▲❏❲❒P❃➱❛❋❵✜✪❯ ✣❫ä ✍✫ ✂❄❒P❈❊■❣❃✃✵ß➩➱❛◆❭❒✽❏✦❋▲➮✣■➽ç✐■✍❃Ð❛❈♥❒✱➱✦❮✕❮➊■❦❏❲❒P❖❊◆P■❏✮ ✎✫ ✂❄❒P❈❊■❣✃✵■❦❏✦❋☞➱✦❮②❋▲❏tÒ❉❃Ð♥❏❲❒P❃➱❛❋☞❑❊❏❲❒✽❏✮❃❋☞❮➊■❦❏❲❒P❖❊◆P■❏✮ ✏✫ ✂❄❒P❈❊■✛◗❇❒✽❏✦❋▲❑❊❏✦◆✽❑☞❑⑧■✍Ò❉❃④❏❲❒P❃➱❛❋☞➱✦❮✕❋▲❏tÒ❉❃Ð♥❏❲❒P❃➱❛❋☞❑❊❏❲❒✽❏✮❃❋☞❮➊■❦❏❲❒P❖❊◆P■❏✮ ✑✫ ✏✓✒✕✔✗✖✗✘ ✖ ✙ ✚ ✖✜✛✣✢✥✤☛✦✥✖ ❃❮✄✮■✜ ✔ ✣✝✆ ✜✎✫★✧ ❚ ❅ ✏✫ ✣ ✱ ❃❮✩✟✫ ✜ ✔ ✣✫✪ ✜✎✫★✧ ❚ ❅ ✏✫ ✣ ✜✪❱ ✣ ✥✌✛✴✜ ✔ ✣ ✏ ✜✍☞✾❅ ✑☞✟✣ ❅❵✜✍■ ❅ ✑■ ✣✞❅❵✜✍✡ ❅ ✑✡ ✣ ✜✪❯ ✣ ✝✖➱✦❒P■☞❒P❈▲❏❲❒①❮➊➱❛◆✵❒P❈❊■✝❋❊➱❛◆P✃①❏✦Ï ❃❰❦❏❲❒P❃➱❛❋➯ß❊❖❊◆Pß➩➱♥◗❭■❛❐✟ç✐■✝❖▲◗❭■✁✜✎✫✬✧ ❚☞❅ ✏✫ ✣✵❏❛◗✮❒P❈❊■ ❖❊ß❊ß➩■✍◆✱❘➩➱❛❖❊❋▲❑➧❃❋✙✟❍Ñ♥❖▲❏❲❒P❃➱❛❋P✜✪❱ ✣❫ä❊æ✸❈❊❃④◗✐❖❊ß❊ß➩■✍◆✱❘➩➱❛❖❊❋▲❑☞➮✍❏✦❋☞ß❊◆P■✍Ò❛■✍❋♥❒❍❒P❈❊■❣❏❲â➤■❦➮❫❒✸❮➊◆P➱❛✃ ➱❛❖⑧❒PÏ ❃■✍◆✽◗✰✯ ✷❆✱✟✸✂➱✦❮✈❒P❈❊■❣❋▲❏tÒ❉❃Ð♥❏❲❒P❃➱❛❋☞❑❊❏❲❒✽❏❊ä ✭ þ✐❥✍❱❇❳➽❱❇✇❉❬✣❱❄➺✸⑦ ➜②❥❦♠♥③❪☞♦✽❥❦❚✦st❳P❩❇❨❦❳❣❧⑧❳P❩✡❳✽st❥❦③♠❛❱❇❵❥❦❚✝❧❛❩❇❥❲♦✽❳✽❞q❞❄❬✍❚❉❪➢❱❇✇♥❳P❩❇❳❣❵ ❞✖❚♥❥✵❨❦♠❉❬✣❩❭❬✍❚❲❱❇❳✽❳ ❱❇✇❉❬✣❱✟❵❱✟♦✽❥❦❚✦st❳P❩❇❨❦❳✽❞✼❬✍♦P❩❇❥❦❞q❞✼❞q❳✽st❳P❩❭❬✍③❊❳✽st❥❦③♠❛❱❇❵❥❦❚♥❞✟❵✉➩❱❇✇♥❳✐♠♥❞q❳P❩❫➥ ❞✟❚❉❬❫s✦❵❨t❬✣❱❇❵❥❦❚✮➝⑧❳✽✇❉❬❫s✦❵❥✍❩✟❵ ❞✟❵❚❛❸ ♦✽❥❦❚♥❞q❵ ❞❡❱❇❳✽❚❲❱❫➟✍➨✐❥❫➜②❳✽st❳P❩❫⑤✣❵❚✖❨❦❳✽❚♥❳P❩❭❬✍③➀⑤❦❚♥❥❍③ ❳❫❬✣❩❇❚♥❵❚♥❨❍❢❣❳✽♦❭✇❉❬✍❚♥❵ ❞q❢ö♦❫❬✍❚❄❪❛❳❫❬✍③t➜✼❵❱❇✇✡❵❚♥♦✽❥❦❚♥❞q❵ ❞❡❱❇❳✽❚❲❱ ➝⑧❳✽✇❉❬❫s✦❵❥✍❩❇❞