Euler's partition theorem and the combinatorics of -sequences

Euler's partition theorem and the combinatorics of -sequences Euler's partition theorem and the combinatorics of -sequences

01.06.2015 Views

Θ (l) : Bijection for the l-Euler Theorem [SY07] Given a partition µ into parts in {a 0 + a 1 , a 1 + a 2 , a 2 + a 3 , . . .} construct λ = (λ 1 , λ 2 , . . .) by inserting the parts of µ in nonincreasing order as follows: To insert a k−1 + a k into (λ 1 , λ 2 , . . .): If k = 1, then add a 1 to λ 1 ; otherwise, if (λ 1 + a k − a k−1 ) > c l (λ 2 + a k−1 − a k−2 ), add a k − a k−1 to λ 1 , add a k−1 − a k−2 to λ 2 ; recursively insert a k−2 + a k−1 into (λ 3 , λ 4 , . . .) otherwise, add a k to λ 1 , and add a k−1 to λ 2 .

The insertion step To insert a k + a k−1 into (λ 1 , λ 2 , λ 3 , λ 4 , . . .) either do (i) (λ 1 + a k , λ 2 + a k−1 , λ 3 , λ 4 , . . .) or (ii) (λ 1 + (a k − a k−1 ), λ 2 + (a k−1 − a k−2 ), insert (a k−1 + a k−2 )into(λ 3 , λ 4 , . . .)) How to decide? Do (ii) if the ratio of first two parts is okay, otherwise do (i).

Θ (l) : Bijection for <strong>the</strong> l-Euler Theorem [SY07]<br />

Given a <strong>partition</strong> µ into parts in<br />

{a 0 + a 1 , a 1 + a 2 , a 2 + a 3 , . . .}<br />

construct λ = (λ 1 , λ 2 , . . .) by inserting <strong>the</strong> parts <strong>of</strong> µ in nonincreasing<br />

order as follows:<br />

To insert a k−1 + a k into (λ 1 , λ 2 , . . .):<br />

If k = 1, <strong>the</strong>n add a 1 to λ 1 ;<br />

o<strong>the</strong>rwise, if (λ 1 + a k − a k−1 ) > c l (λ 2 + a k−1 − a k−2 ),<br />

add a k − a k−1 to λ 1 , add a k−1 − a k−2 to λ 2 ;<br />

recursively insert a k−2 + a k−1 into (λ 3 , λ 4 , . . .)<br />

o<strong>the</strong>rwise,<br />

add a k to λ 1 , <strong>and</strong> add a k−1 to λ 2 .

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