Multidimentional Scaling Trung Duc Tran Institute of Mathematics University of Silesia in Katowice 1 1 Introduction we suppose that there are n objects 1, , n, and that we have experimental values σij.
▼✉❧t✐❞✐♠❡♥t✐♦♥❛❧ ❙❝❛❧✐♥❣ ❚r✉♥❣ ❉✉❝ ❚r❛♥ ■♥st✐t✉t❡ ♦❢ ▼❛t❤❡♠❛t✐❝s ❯♥✐✈❡rs✐t② ♦❢ ❙✐❧❡s✐❛ ✐♥ ❑❛t♦✇✐❝❡ ✶ ✶✳ ■♥tr♦❞✉❝t✐♦♥ ✇❡ s✉♣♣♦s❡ t❤❛t t❤❡r❡ ❛r❡ ♥ ♦❜❥❡❝ts ✶✱✳✳ ✱ ♥✱ ❛♥❞ t❤❛t ✇❡ ❤❛✈❡ ❡①♣❡r✐♠❡♥t❛❧ ✈❛❧✉❡s σij ♦❢ ❞✐ss✐♠✐❧❛r✐t② ❜❡t✇❡❡♥ t❤❡♠✳ ❋♦r ❛ ❝♦♥✜❣✉r❛t✐♦♥ ♦❢ ♣♦✐♥ts x1 , , xn ✐♥ t✲❞✐♠❡♥s✐♦♥❛❧ s♣❛❝❡✱ ✇✐t❤ ✐♥t❡r♣♦✐♥t ❞✐st❛♥❝❡s dij ✱ ✇❡ ❞❡✜♥❡❞ t❤❡ str❡ss ♦❢ t❤❡ ❝♦♥✲ ✜❣✉r❛t✐♦♥ ❜② ✭✶✳✶✮ S= S1 = T1 (dij − dˆij )2 d2ij ❲❡ ❞❡✜♥❡ ❛ str❡ss ❢✉♥❝t✐♦♥ ✐♥ ❘ ✿ ✇❤❡r❡ t❤❡ ✈❛❧✉❡s ♦❢ dˆij ❛r❡ t❤♦s❡ ♥✉♠❜❡rs ✇❤✐❝❤ ♠✐♥✐♠✐③❡ ❙ s✉❜❥❡❝t t♦ t❤❡ ❝♦♥str❛✐♥t t❤❛t t❤❡ dˆij ❤❛✈❡ t❤❡ s❛♠❡ r❛♥❦ ♦r❞❡r ❛s t❤❡ σij ❚❤❡ str❡ss ✐s ✐♥t❡♥❞❡❞ t♦ ❜❡ ❛ ♠❡❛s✉r❡ ♦❢ ❤♦✇ ✇❡❧❧ t❤❡ ❝♦♥✜❣✉r❛t✐♦♥ ♠❛t❝❤❡s t❤❡ ❞❛t❛ ❇② ❞❡✜♥✐t✐♦♥✱ t❤❡ ❜❡st✲✜tt✐♥❣ ❝♦♥✜❣✉r❛t✐♦♥ ✐♥ t✲❞✐♠❡♥s✐♦♥❛❧ s♣❛❝❡✱ ❢♦r ❛ ✜①❡❞ ✈❛❧✉❡ ♦❢ t✱ ✐s t❤❛t ❝♦♥✜❣✉r❛t✐♦♥ ✇❤✐❝❤ ♠✐♥✐♠✐③❡s t❤❡ str❡ss ❖❢ ♠❛❥♦r ✐♥t❡r❡st ✐s t❤❡ ♦r❞✐♥❛r② ❝❛s❡ ✐♥ ✇❤✐❝❤ t❤❡ ❞✐st❛♥❝❡s ❛r❡ ❊✉❝❧✐❞❡❛♥✳ ■❢ t❤❡ ♣♦✐♥t xi ✱ ❤❛s ✭ ♦rt❤♦❣♦♥❛❧✮ ❝♦♦r❞✐♥❛t❡s xi1 , , xit t❤❡♥ t❤❡ ❊✉❝❧✐❞❡❛♥ ✭♦r P②t❤❛❣♦r❡❛♥✮ ❞✐st❛♥❝❡ ❢r♦♠ xi ✱ t♦ xj ✐s ❣✐✈❡♥ ❜② l=t ✭✶✳✷✮ (xil − xjl )2 dij = l=1 ❲❡ ❞❡✜♥❡ ❛ ❞✐st❛♥❝❡ ❢✉♥❝t✐♦♥ ✐♥ ❘ ✿ ✷✳ ◆✉♠❡r✐❝❛❧ ❚❡❝❤♥✐q✉❡ ■♥ ♣r✐♥❝✐♣❧❡ t❤❡ ✐t❡r❛t✐✈❡ t❡❝❤♥✐q✉❡ ✇❡ ✉s❡ t♦ ♠✐♠♠✐③❡ t❤❡ str❡ss ✐s ♥♦t ❞✐✣❝✉❧t✳ ■t r❡q✉✐r❡s st❛rt✐♥❣ ❢r♦♠ ❛♥ ❛r❜✐tr❛r② ❝♦♥✜❣✉r❛t✐♦♥✱ ❝♦♠♣✉t✐♥❣ t❤❡ ✭♥❡❣❛t✐✈❡✮ ❣r❛❞✐❡♥t✱ ♠♦✈✐♥❣ ❛❧♦♥❣ ✐t ❛ s✉✐t❛❜❧❡ ❞✐st❛♥❝❡✱ ❛♥❞ t❤❡♥ r❡♣❡❛t✐♥❣ t❤❡ ❧❛st t✇♦ st❡♣s ❛ s✉✣❝✐❡♥t ♥✉♠❜❡r ♦❢ t✐♠❡s✳ ■❢ ❛ ❢❛✐r❧② ❣♦♦❞ ❝♦♥✜❣✉r❛t✐♦♥ ✐s ❝♦♥✈❡♥✐❡♥t❧② ❛✈❛✐❧❛❜❧❡ ❢♦r ✉s❡ ❛s t❤❡ st❛rt✐♥❣ ❝♦♥✜❣✉r❛t✐♦♥✱ ✐t ♠❛② s❛✈❡ q✉✐t❡ ❛ ❢❡✇ ✐t❡r❛t✐♦♥s✳ ■❢ ♥♦t✱ ❛♥ ❛r❜✐tr❛r② st❛rt✐♥❣ ❝♦♥✜❣✉r❛t✐♦♥ ✐s q✉✐t❡ s❛t✐s❢❛❝t♦r②✳ ❖♥❧② t✇♦ ❝♦♥❞✐t✐♦♥s s❤♦✉❧❞ ❜❡ ♠❡t✿ ♥♦ t✇♦ ♣♦✐♥ts ✐♥ t❤❡ ❝♦♥✜❣✉r❛t✐♦♥ s❤♦✉❧❞ ❜❡ t❤❡ s❛♠❡✱ ❛♥❞ t❤❡ ❝♦♥✜❣✉r❛t✐♦♥ s❤♦✉❧❞ ✷ ♥♦t ❧✐❡ ✐♥ ❛ ❧♦✇❡r✲❞✐♠❡♥s✐♦♥❛❧ s✉❜s♣❛❝❡ t❤❛♥ ❤❛s ❜❡❡♥ ❝❤♦s❡♥ ❢♦r t❤❡ ❛♥❛❧②s✐s✳ ■❢ ♥♦ ❝♦♥✜❣✉r❛t✐♦♥ ✐s ❝♦♥✈❡♥✐❡♥t❧② ❛✈❛✐❧❛❜❧❡✱ ❛♥ ❛r❜✐tr❛r② ❝♦♥✜❣✉r❛t✐♦♥ ♠✉st ❜❡ ❣❡♥❡r❛t❡❞✳ ❖♥❡ s❛t✐s❢❛❝t♦r② ✇❛② t♦ ❞♦ t❤✐s ✐s t♦ ✉s❡ t❤❡ ✜rst ♥ ♣♦✐♥ts ❢r♦♠ t❤❡ ❧✐st (1, 0, 0, 0, 0), (0, 1, 0, 0, 0), (0, 0, 0, 0, 1), (2, 0, 0, 0, 0), (0, 2, 0, , 0, 0), etc ❙♦ ✇❡ ❤❛✈❡ t❤❡ ❝♦❞❡ ✐♥ ❘ ✿ ❙✉♣♣♦s❡ ✇❡ ❤❛✈❡ ❛rr✐✈❡❞ ❛t t❤❡ ❝♦♥✜❣✉r❛t✐♦♥ ①✱ ❝♦♥s✐st✐♥❣ ♦❢ t❤❡ ♥ ♣♦✐♥ts x1 , , xn ✐♥ t ❞✐♠❡♥s✐♦♥s✳ ▲❡t t❤❡ ❝♦♦r❞✐♥❛t❡s ♦❢ xi ❜❡ xi1 , , xit ❲❡ s❤❛❧❧ ❝❛❧❧ ❛❧❧ t❤❡ ♥✉♠❜❡rs xis ✱ ✇✐t❤ ✐ ❂ ✶✱ ✳✳ ✱ ♥ ❛♥❞ s ❂ ✶✱ ✳✳ ✱ t✱ t❤❡ ❝♦♦r❞✐♥❛t❡s ♦❢ t❤❡ ❝♦♥✜❣✉r❛t✐♦♥ ①✳ ❙✉♣♣♦s❡ t❤❡ ✭♥❡❣❛t✐✈❡✮ ❣r❛❞✐❡♥t ♦❢ str❡ss ❛t ① ✐s ❣✐✈❡♥ ❜② ❣✱ ✇❤♦s❡ ❝♦♦r❞✐♥❛t❡s ❛r❡ gis ✳ ❚❤❡♥ ✇❡ ❢♦r♠ t❤❡ ♥❡①t ❝♦♥✜❣✉r❛t✐♦♥ ❜② st❛rt✐♥❣ ❢r♦♠ ① ❛♥❞ ♠♦✈✐♥❣ ❛❧♦♥❣ ❣ ❛ ❞✐st❛♥❝❡ ✇❤✐❝❤ ✇❡ ❝❛❧❧ t❤❡ st❡♣✲s✐③❡ α✳ ■♥ s②♠❜♦❧s✱ t❤❡ ♥❡✇ ❝♦♥✜❣✉r❛t✐♦♥ ①✬ ✐s ❣✐✈❡♥ ❜② xis = xis + α ∗ gis mag(g) ❢♦r ❛❧❧ ✐ ❛♥❞ s✳ ❍❡r❡ ♠❛❣ ✭❣✮ ♠❡❛♥s t❤❡ r❡❧❛t✐✈❡ ♠❛❣♥✐t✉❞❡ ♦❢ ❣ ❛♥❞ ✐s ❣✐✈❡♥ ❜②✿ gis / mag(g) = i,s x2is i,s ❚❤❡ ✐♥✐t✐❛❧ ✈❛❧✉❡ ♦❢ α ✇✐t❤ ❛♥ ❛r❜✐tr❛r② st❛rt✐♥❣ ❝♦♥✜❣✉r❛t✐♦♥ s❤♦✉❧❞ ❜❡ ❛❜♦✉t ✵✳✷✳ ❋♦r ❛ ❝♦♥✜❣✉r❛t✐♦♥ t❤❛t ❛❧r❡❛❞② ❤❛s ❧♦✇ str❡ss✱ ❛ s♠❛❧❧❡r ✈❛❧✉❡ s❤♦✉❧❞ ❜❡ ✉s❡❞✳ ✭❆ ♣♦♦r❧② ❝❤♦s❡♥ ✈❛❧✉❡ r❡s✉❧ts ♦♥❧② ✐♥ ❡①tr❛ ✐t❡r❛t✐♦♥s✳✮ ❚♦ ❝❛❧❝✉❧❛t❡ t❤❡ ✭♥❡❣❛t✐✈❡✮ ❣r❛❞✐❡♥t ✇❡ ✉s❡ t❤❡ ❢♦❧❧♦✇✐♥❣ ❢♦r♠✉❧❛s✳ ❋♦r ❊✉❝❧✐❞❡❛♥ ❞✐st❛♥❝❡ r ❂ ✷ ✿ (σ ki − σ kj ) gkl = S i,j dij − dˆij dij − S1 T1 (xil − xjl ) dij ✸ ❍❡r❡ σ ki ❛♥❞ σ kj ❞❡♥♦t❡ t❤❡ ❑r♦♥❡❝❦❡r s②♠❜♦❧s T1 = S1 = d2ij (dij − dˆij )2 ❲❡ ❞❡✜♥❡ ❛ ❣r❛❞✐❡♥t ❢✉♥❝t✐♦♥ ✿ ❆♥❞ t❤❡ ❢✉♥❝t✐♦♥ ❢♦r ♥❡①t ❝♦♥✜❣✉r❛t✐♦♥ ✿ ❍❡r❡ ✇❡ ❤❛✈❡ ❛❧♣❤❛ ❂✵✳✷✷✺✼✶✵✻ ❜② ❛♣♣❧② t❤❡ ❢♦r♠✉❧❛s ❢r♦♠ t❤❡ ♣r❡✈✐♦✉s ❝❤❛♣t❡r ❇② ❞♦✐♥❣ t❤❡ ❧♦♦♣ ♠❛♥② t✐♠❡ ✉♥t✐❧ t❤❡ str❡ss ❁✻% ✹ ❲❡ ❝❛♥ s❛t✐s❢② ✇✐t❤ t❤✐s str❡ss ❋✐♥❛❧❧②✱ ✇❡ ♣r✐♥t ♦✉t t❤❡ r❡s✉❧t ❲❡ ❝❛♥ ❡❛s✐❧② s❡❡ t❤❛t ✸ t②♣❡s ♦❢ ✢♦✇❡r ❛r❡ s❡♣❛r❛t❡❞ ✐♥ t❤❡ ❣r❛♣❤