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Dec 03, 2023 270 likes •472 views

qt t trt tst qt t r qt t

SLIDE 1

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥

SLIDE 2

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

❙✉♠♠❛r②

■♥tr♦❞✉❝t✐♦♥ ❬❈❤❛♥❣✲▲❡❡ ❈❤✳ ✽✳✶❪ ❊✲❙❛t✐s✜❛❜✐❧✐t② ❬❈❤❛♥❣✲▲❡❡ ❈❤✳ ✽✳✷❪

SLIDE 3

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

■♠♣♦rt❛♥❝❡ ♦❢ ❊q✉❛❧✐t② ❘❡❧❛t✐♦♥

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ❱❡r② ✐♠♣♦rt❛♥t r❡❧❛t✐♦♥ ✇✐t❤ s♣❡❝✐❛❧ ♣r♦♣❡rt② ▼❛♥② t❤❡♦r✐❡s ♥❡❡❞ ❡q✉❛❧✐t② ◆✉♠❜❡r t❤❡♦r②✿

♦♥❡ s♦♥st❛♥t✱ ♦♥❡ s✉❝❝❡ss♦r ❢✉♥❝t✐♦♥ ❡q✉❛❧✐t② r❡❧❛t✐♦♥

SLIDE 4

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

Pr♦♣❡rt✐❡s ♦❢ ❊q✉❛❧✐t② ❘❡❧❛t✐♦♥

Pr♦♣❡rt✐❡s ❙♣❡❝✐❛❧ ♣r♦♣❡rt✐❡s ♦❢ ❡q✉❛❧✐t②✿

r❡✢❡①✐✈✐t② s②♠♠❡tr② tr❛♥s✐t✐✈✐t②

❙✉❜st✐t✉t❡ ❡q✉❛❧s ❢♦r ❡q✉❛❧s ❲❤❡♥ ✉s✐♥❣ ❡q✉❛❧✐t② ✇❡ ♥❡❡❞ ❡①tr❛ ❛①✐♦♠s t♦ ❡①♣r❡ss t❤❡s❡ ♣r♦♣❡rt✐❡s

SLIDE 5

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

❊①❛♠♣❧❡✿ ❈♦♠♠✉t❛t✐✈❡ ❣r♦✉♣s

❊①❛♠♣❧❡ ✭❈♦♠♠✉t❛t✐✈❡ ●r♦✉♣s✮ ❈♦♥s✐❞❡r t❤❡ t❤❡♦r❡♠✿ ■❢ ① ◦ ① = ❡ ❢♦r ❛❧❧ ① ∈ ● ✇❤❡r❡ ● ✐s ❛ ❣r♦✉♣✱ ◦ ✐s t❤❡ ❜✐♥❛r② ♦♣❡r❛t✐♦♥ ♦❢ t❤❡ ❣r♦✉♣ ❛♥❞ ❡ ✐s t❤❡ ♥✉❧❧ ❡❧❡♠❡♥t ♦❢ ●✱ t❤❡♥ ● ✐s ❝♦♠♠✉t❛t✐✈❡✳ ❢♦r♠❛❧✐s❛t✐♦♥ ❆✶ (∀①)(∀②)(∃③)(① ◦ ② = ③) ✭❝❧♦s✉r❡✮ ❆✷ (∀①)(∀②)(∀③)(① ◦ (② ◦ ③) = (① ◦ ②) ◦ ③) ✭❛ss♦❝✐❛t✐✈✐t②✮ ❆✸ (∀①)((① ◦ ❡ = ①) ∧ (❡ ◦ ① = ①)) ✭✐❞❡♥t✐t②✮ ❆✹ (∀①)((① ◦ ✐(①) = ❡) ∧ (✐(①) ◦ ① = ❡)) ✭✐♥✈❡rs❡✮ ❇ (∀①)(① ◦ ① = ❡) → ((∀✉)(∀✈)(✉ ◦ ✈ = ✈ ◦ ✉)) ✭t❤❡♦r❡♠ t❤❡s✐s✮

SLIDE 6

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

❊①❛♠♣❧❡✿ ❈♦♠♠✉t❛t✐✈❡ ❣r♦✉♣s

❝❧❛✉s❡s ❆✶ ∧❆✷ ∧❆✸ ∧❆✹ ∧¬❇ ▲❡t ❙∗ ❜❡ t❤❡ ✉♥✐♦♥ ♦❢ ❢♦❧❧♦✇✐♥❣ ❝❧❛✉s❡s✿

✶ ① ◦ ② = ❢ (①, ②) ✷ ① ◦ (② ◦ ③) = (① ◦ ②) ◦ ③ ✸ ① ◦ ❡ = ① ✹ ❡ ◦ ① = ① ✺ ① ◦ ✐(①) = ❡ ✻ ✐(①) ◦ ① = ❡ ✼ ① ◦ ① = ❡ ✽ ❛ ◦ ❜ = ❜ ◦ ❛

❆♣♣❧②✐♥❣ r❡s♦❧✉t✐♦♥ ❝❛♥ ✇❡ ✜♥❞ ❄

SLIDE 7

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

❊①♣r❡ss✐♥❣ ❊q✉❛❧✐t②

❊①♣r❡ss✐♥❣ ❊q✉❛❧✐t② ▲❡t ❑ ❜❡ t❤❡ ✉♥✐♦♥ ♦❢ ❢♦❧❧♦✇✐♥❣ ❝❧❛✉s❡s

✶ ① = ① ✭r❡✢❡①✐✈✐t②✮ ✷ ① = ② ∨ ② = ① ✭① = ② → ② = ①✮ ✭s②♠♠❡tr②✮ ✸ ① = ② ∨ ② = ③ ∨ ① = ③ ✭tr❛♥s✐t✐✈✐t②✮ ✹ ① = ② ∨ ① = ✉ ∨ ② = ✉ ✭s✉❜s✳ ❢♦r ❡q✉❛❧s✮ ✺ ① = ② ∨ ✉ = ① ∨ ✉ = ② ✭s✉❜s✳ ❢♦r ❡q✉❛❧s✮ ✻ ① = ② ∨ ❢ (①, ③) = ❢ (②, ③) ✭s✉❜s✳ ❢♦r ❡q✉❛❧s✮ ✼ ① = ② ∨ ❢ (③, ①) = ❢ (③, ②) ✭s✉❜s✳ ❢♦r ❡q✉❛❧s✮ ✽ ① = ② ∨ ① ◦ ③ = ② ◦ ③ ✭s✉❜s✳ ❢♦r ❡q✉❛❧s✮ ✾ ① = ② ∨ ③ ◦ ① = ③ ◦ ② ✭s✉❜s✳ ❢♦r ❡q✉❛❧s✮ ✶✵ ① = ② ∨ ✐(①) = ✐(②) ✭s✉❜s✳ ❢♦r ❡q✉❛❧s✮

SLIDE 8

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

■ss✉❡s ✇✐t❤ ❡♣r❡ss✐♥❣ ❡q✉❛❧✐t② ❛①✐♦♠s

✐ss✉❡s

✶ ❚❤❡ s❡t ❙ ∪ ❑ ✐s ✉♥s❛t✐s✜❛❜❧❡✳ ✷ ❯s✐♥❣ r❡s♦❧✉t✐♦♥ ♦♥ ❙ ∪ ❑ ✇❡ ✇✐❧❧ ✜♥❞ ❜✉t✳✳✳ ✸ ❊✈❡r② t✐♠❡ ✇❡ ❤❛✈❡ ❡q✉❛❧✐t② ✇❡ ❤❛✈❡ t♦ ❛❞❞ ❑ t♦ t❤❡ s❡t

✇❡ ✇❛♥t t♦ r❡❢✉t❡

✹ ❲❡ ✉s❡ ♠✉❝❤ ♠♦r❡ ❝❧❛✉s❡s ✺ ❲❡ ✇✐❧❧ ❣❡♥❡r❛t❡ ♠❛♥② r❡❞✉♥❞❛♥t ❝❧❛✉s❡s

SLIDE 9

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

❙♣❡❝✐❛❧ ❝❧❛ss❡s ♦❢ ♠♦❞❡❧s

❝❧❛ss❡s ♦❢ ♠♦❞❡❧s ❙ ✉♥s❛t ✐✛ ❙ ✐s ❢❛❧s❡ ✉♥❞❡r ❛❧❧ ♣♦ss✐❜❧❡ ✐♥t❡r♣r❡t❛t✐♦♥s ✭♦r ❍✲■♥t❡r♣r❡t❛t✐♦♥✮ ❍♦✇❡✈❡r✱ ✇❡ ❝❛♥ ✐❞❡♥t✐❢② ✐♥t❡r❡st✐♥❣ s✉❜s❡ts ♦❢ ✐♥t❡r♣r❡t❛t✐♦♥s ❢♦r ✇❤✐❝❤ ❙ ✉♥s❛t ❊①❛♠♣❧❡ ✭■♥t❡r❡st✐♥❣ s✉❜s❡t ♦❢ ✐♥t❡r♣r❡t❛t✐♦♥s✮ ❈♦♥s✐❞❡r ♣r❡✈✐♦✉s t❤❡♦r❡♠✿ ❙∗ ✐s s❛t✐s✜❛❜❧❡ ❍♦✇❡✈❡r✱ ❙∗ ✐s ✉♥s❛t✐s✜❛❜❧❡ ❢♦r ❛❧❧ ✐♥t❡r♣r❡t❛t✐♦♥s t❤❛t s❛t✐s❢② ❑

SLIDE 10

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

◗✲❙❛t✐s✜❛❜✐❧✐t②

❉❡✜♥✐t✐♦♥ ✭◗✲❙❛t✐s✜❛❜✐❧✐t②✮ ❙ s❡t ♦❢ ❝❧❛✉s❡s ❲ ❛❧❧ ✐♥t❡r♣r❡t❛t✐♦♥s ♦❢ ❙ ◗ ⊆ ❲ ✱ ◗ = { } ❙ ◗✲✉♥s❛t✐s✜❛❜❧❡ ✐✛ ❙ ❢❛❧s❡ ❢♦r ❡✈❡r② ✐♥t❡r♣r❡t❛t✐♦♥ ✐♥ ◗

SLIDE 11

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

❙♣❡❝✐❢②✐♥❣ ◗

❚❤❡♦r② ❢♦r ◗ ◆❡❡❞ ❛ ✇❛② t♦ s♣❡❝✐❢② ◗ ◗ ✜♥✐t❡✿ ❧✐st ❛❧❧ ❡❧❡♠❡♥ts ◗ ♥♦t ✜♥✐t❡✿ ❣✐✈❡ ❛ t❤❡♦r② s♣❡❝✐❢②✐♥❣ ◗ ❚❤❡♦r② ❚✿ ❝♦♥❥✉♥❝t✐♦♥ ♦❢ ❛①✐♦♠s ◗ ❛❧❧ ✐♥t❡r♣r❡t❛t✐♦♥s t❤❛t s❛t✐s❢② ❚ ❊①❛♠♣❧❡ ✭❚❤❡♦r② ❑✮ ◗✿ ❛❧❧ ♠♦❞❡❧s ♦❢ ❑✳ ❙∗ ✐s ◗✲✉♥s❛t✐s✜❛❜❧❡ ❑ ✐s t❤❡ t❤❡♦r② t❤❛t ❞❡✜♥❡s ❡q✉❛❧✐t② ❛①✐♦♠s ❢♦r ❙∗✱ t❤❡r❡❢♦r❡ ❙∗ ✐s ❊✲✉♥s❛t✐s✜❛❜❧❡✳

SLIDE 12

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

❊✲■♥t❡r♣r❡t❛t✐♦♥

❙♣❡❝✐❢②✐♥❣ ■♥t❡r♣r❡t❛t✐♦♥s ❢♦r ❊q✉❛❧✐t②

✐✈❡♥ ❛ s❡t ❙✱ ✇❡ ❝❛♥ s♣❡❝✐❢② ❛ ❣❡♥❡r❛❧ ❝❧❛ss ♦❢ ■♥t❡r♣r❡t❛t✐♦♥s

❢♦r ❡q✉❛❧✐t② ❛①✐♦♠s✳ ❉❡✜♥✐t✐♦♥ ✭❊✲■♥t❡r♣r❡t❛t✐♦♥✮ ❙ s❡t ♦❢ ❝❧❛✉s❡s α, β, γ t❡r♠s ♦❢ t❤❡ ❍❡r❜r❛♥❞ ✉♥✐✈❡rs❡ ♦❢ ❙✳ ■ ✐♥t❡r♣r❡t❛t✐♦♥ ❢♦r ❙✱ ❛ ▲ ❧✐t❡r❛❧ ✐♥ ■ ■ ✐s ❛♥ ❊✲✐♥t❡r♣r❡t❛t✐♦♥ ✐❢ t❤❡ ❢♦❧❧♦✇✐♥❣ ❤♦❧❞✿

(α = α) ∈ ■ ✐❢ (α = β) ∈ ■ t❤❡♥ β = α ∈ ■ ✐❢ (α = β) ∈ ■ ❛♥❞ β = γ ∈ ■ t❤❡♥ α = γ ∈ ■ ✐❢ (α = β) ∈ ■ ❛♥❞ ▲′ ❛ ❧✐t❡r❛❧ ♦❜t❛✐♥❡❞ ❜② r❡♣❧❛❝✐♥❣ ❛♥ ♦❝❝✉rr❡♥❝❡ ♦❢ α ✐♥ ▲ ✇✐t❤ β t❤❡♥ ▲′ ∈ ■

SLIDE 13

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

❊✲❙❛t✐s✜❛❜❧❡ ❙❡t

❙♣❡❝✐❢②✐♥❣ ■♥t❡r♣r❡t❛t✐♦♥s ❢♦r ❊q✉❛❧✐t② ❆♥ ❊✲■♥t❡r♣❡t❛t✐♦♥ ✐s ❛♥② ✐♥t❡r♣r❡t❛t✐♦♥ t❤❛t s❛t✐s✜❡s t❤❡ r❡✢❡①✲ ✐✈✐t②✱ s②♠♠❡tr✐❝✱ tr❛♥s✐t✐✈✐t② ❛♥❞ s✉❜st✐t✉t✐✈❡ ❛①✐♦♠s ♦❢ ❡q✉❛❧✐t②✳ ❉❡✜♥✐t✐♦♥ ✭❊✲❙❛t✐s✜❛❜❧❡ ❙❡t✮ ❙ ❛ s❡t ♦❢ ❝❧❛✉s❡s ❙ ✐s ❊✲s❛t✐s✜❛❜❧❡ ✐✛ t❤❡r❡ ✐s ❛♥ ❊✲✐♥t❡r♣r❡t❛t✐♦♥ t❤❛t s❛t✐s✜❡s ❛❧❧ ❝❧❛✉s❡s ✐♥ ❙✳

SLIDE 14

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

❊①❛♠♣❧❡

❊①❛♠♣❧❡ ✭❊✲❯♥s❛t✐s✜❛❜❧❡ ❙❡t✮ ❈♦♥s✐❞❡r ❙ {P(❛), ¬P(❜), ❛ = ❜} ✭❤♦✇ ♠❛♥② ♣♦ss✐❜❧❡ ✐♥t❡r♣r❡t❛t✐♦♥s ❄✮ ❊✲■♥t❡r♣r❡t❛t✐♦♥s ❢♦r ❙✿ {P(❛), P(❜), ❛ = ❛, ❜ = ❜, ❛ = ❜, ❜ = ❛} {P(❛), P(❜), ❛ = ❛, ❜ = ❜, ❛ = ❜, ❜ = ❛} {¬P(❛), ¬P(❜), ❛ = ❛, ❜ = ❜, ❛ = ❜, ❜ = ❛} {¬P(❛), ¬P(❜), ❛ = ❛, ❜ = ❜, ❛ = ❜, ❜ = ❛} {¬P(❛), P(❜), ❛ = ❛, ❜ = ❜, ❛ = ❜, ❜ = ❛} {P(❛), ¬P(❜), ❛ = ❛, ❜ = ❜, ❛ = ❜, ❜ = ❛} ❙ ✐s ❊✲✉♥s❛t✐s✜❛❜❧❡✳

SLIDE 15

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

❙❡t ♦❢ ❡q✉❛❧✐t② ❛①✐♦♠s

❙❡t ♦❢ ❡q✉❛❧✐t② ❛①✐♦♠s ❢♦r ❛ s❡t ❙

✐✈❡♥ ❛ s❡t ✇❡ ✇❛♥t t♦ s♣❡❝✐❢② t❤❡ ❛①✐♦♠s t❤❛t ❡①♣r❡ss t❤❡ ♣r♦♣✲

❡rt✐❡s ♦❢ ❡q✉❛❧✐t② ❢♦r t❤❛t s❡t ❑ ✐s s✉❝❤ ❛ s❡t ❢♦r ❙∗✳ ❉❡✜♥✐t✐♦♥ ✭❙❡t ♦❢ ❡q✉❛❧✐t② ❛①✐♦♠s ❢♦r ❙✮

❙✿ s❡t ♦ ❝❧❛✉s❡s ① = ① ① = ② ∨ ② = ① ① = ② ∨ ② = ③ ∨ ① = ③ ①❥ = ①✵ ∨ ¬P(①✶, · · · , ①❥, · · · , ①♥) ∨ P(①✶, · · · , ①✵, · · · , ①♥) ❢♦r ❥ = ✶, · · · , ♥ ❢♦r ❡✈❡r② ♥✲♣❧❛❝❡ ♣r❡❞✐❝❛t❡ s②♠❜♦❧ P ♦❝❝✉rr✐♥❣ ✐♥ ❙ ①❥ = ①✵ ∨ ❢ (①✶, · · · , ①❥, · · · , ①♥) = ❢ (①✶, · · · , ①✵, · · · , ①♥) ❢♦r ❥ = ✶, · · · , ♥ ❢♦r ❡✈❡r② ♥✲♣❧❛❝❡ ❢✉♥❝t✐♦♥ s②♠❜♦❧ ❢ ♦❝❝✉rr✐♥❣ ✐♥ ❙

SLIDE 16

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

❊✲❙❛t✐s✜❛❜✐❧✐t② ❛♥❞ ❙❛t✐s✜❛❜✐❧✐t②

❚❤❡♦r❡♠ ✭❊✲❙❛t✐s✜❛❜✐❧✐t②✮ ❙✿ s❡t ♦❢ ❝❧❛✉s❡s ❑✿ s❡t ♦❢ ❡q✉❛❧✐t② ❛①✐♦♠s ❢♦r ❙ ❙ ✐s ❊✲✉♥s❛t✐s✜❛❜❧❡ ✐✛ (❙ ∪ ❑) ✐s ✉♥s❛t✐s✜❛❜❧❡✳

SLIDE 17

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

❊✲❙❛t✐s✜❛❜✐❧✐t② ❛♥❞ ❙❛t✐s✜❛❜✐❧✐t②✿ ♣r♦♦❢ s❦❡t❝❤

s❦❡t❝❤✳ ⇒ ❙ ✐s ❊✲✉♥s❛t✳ ❛♥❞ (❙ ∪ ❑) s❛t✳ ■ | = (❙ ∪ ❑) ■ | = ❑ t❤❡♥ ■ ✐s ❛♥ ❊✲✐♥t❡r♣r❡t❛t✐♦♥ ■ | = ❙ ❜✉t ❙ ✐s ❊✲✉♥s❛t✳ ⇐ (❙ ∪ ❑) ✐s ✉♥s❛t✳ ❛♥❞ ❙ ✐s ❊✲s❛t✳ ■❊ | = ❙ ❛♥❞ ■❊ ✐s ❊✲✐♥t❡r♣r❡t❛t✐♦♥s ■❊ | = ❑ ❜❡❝❛✉s❡ ✐s ❛♥ ❊✲✐♥t❡r♣r❡t❛t✐♦♥ ■❊ | = ❙ ∪ ❑ ❜✉t (❙ ∪ ❑) ✐s ✉♥s❛t✳

SLIDE 18

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

❍❡r❜r❛♥❞✬s t❤❡♦r❡♠ ❛♥❞ ❊✲s❛t✐s✜❛❜✐❧✐t②

❚❤❡♦r❡♠ ❙✿ ✜♥✐t❡ s❡t ♦❢ ❝❧❛✉s❡s ❙′✿ ❛ ✜♥✐t❡ s❡t ♦❢ ❣r♦✉♥❞ ✐♥st❛♥❝❡s ♦❢ ❝❧❛✉s❡s ✐♥ ❙ ❙ ✐s ❊✲✉♥s❛t ✐✛ ❡①✐sts ❙′ ✇❤✐❝❤ ✐s ❊✲✉♥s❛t✳

SLIDE 19

❊q✉❛❧✐t② ❘❡❧❛t✐♦♥ ■♥tr♦❞✉❝t✐♦♥ ❊✲ ❙❛t✐s✜❛❜✐❧✐t②

❍❡r❜r❛♥❞✬s t❤❡♦r❡♠ ❛♥❞ ❊✲s❛t✐s✜❛❜✐❧✐t②✿ ♣r♦♦❢ s❦❡t❝❤

s❦❡t❝❤✳ ⇒ ❙ ✐s ❊✲✉♥s❛t✳ t❤❡♥ ❡①✐sts ❙′ ✜♥✐t❡ ❣r♦✉♥❞ ❊✲✉♥s❛t✳ ❑ ❡q✉❛❧✐t② ❛①✐♦♠s ❢♦r ❙✳ ❙ ∪ ❑ ✉♥s❛t✳ ❜② ♣r❡✈✐♦✉s t❤❡♦r❡♠ ❇② ❍❡r❜r❛♥❞✬s t❤❡♦r❡♠ ❡①✐sts ❙′ ❣♦✉♥❞ s✉❝❤ t❤❛t ❙′ ∪ ❑ ✉♥s❛t✳ t❤❡♥ ❜② ♣r❡✈✐♦✉s t❤❡♦r❡♠ ❙′ ✐s ❊✲✉♥s❛t✳ ⇐ ❡①✐sts ❙′ ✜♥✐t❡ ❣r♦✉♥❞ ❊✲✉♥s❛t t❤❡♥ ❙ ✐s ❊✲✉♥s❛t✳ ■❊ | = ❙′ ❢♦r ❛❧❧ ❊✲✐♥t❡r♣r❡t❛t✐♦♥s ■❊ | = ❙