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Order Optimal Information SpreadingUsing Algebraic Gossip
Chen Avin, Michael Borokhovich, Keren Censor-Hillel, Zvi Lotker
Communication Systems Engineering, BGU, Israel
Computer Science and Artificial Intelligence Laboratory, MIT, USA
PODC 2011
The k -Dissemination Problem
1/12
v1 v2
v3 v4
v5
v6
v7
v8
x1 = 5 x2 = 15
x3 = 10 x4 = 12
all nodes need all the k values
as quickly as possible
UniformAlgebraicGossip
Tree BasedAlgebraicGossip
The k -Dissemination Problem
1/12
v1 v2
v3 v4
v5
v6
v7
v8
x1 = 5 x2 = 15
x3 = 10 x4 = 12
all nodes need all the k values
as quickly as possible
UniformAlgebraicGossip
Tree BasedAlgebraicGossip
Gossip Algorithm
2/12
what is algebraic gossip?
Gossip Algorithm
2/12
Time is measuredin rounds
choose a partner
uniformlynon
uniformly
send a message
push pull exch.
message content
?
v1 v2
v3 v4
v5
v6
v7
v8
v1 v2
v3 v4
v5
v6
v7
v8v1 v2
v3 v4
v5
v6
v7
v8
Gossip Algorithm
2/12
Time is measuredin rounds
choose a partner
uniformlynon
uniformly
send a message
push pull exch.
message content
?
v1 v2
v3 v4
v5
v6
v7
v8
v1 v2
v3 v4
v5
v6
v7
v8
v1 v2
v3 v4
v5
v6
v7
v8
Gossip Algorithm
2/12
Time is measuredin rounds
choose a partner
uniformlynon
uniformly
send a message
push pull exch.
message content
?
v1 v2
v3 v4
v5
v6
v7
v8v1 v2
v3 v4
v5
v6
v7
v8
v1 v2
v3 v4
v5
v6
v7
v8
Gossip Algorithm
2/12
Time is measuredin rounds
choose a partner
uniformlynon
uniformly
send a message
push pull exch.
message content
?
v1 v2
v3 v4
v5
v6
v7
v8v1 v2
v3 v4
v5
v6
v7
v8
v1 v2
v3 v4
v5
v6
v7
v8
Algebraic Gossip
3/12
instead of sending randomly chosen values...
every message – a single value
v1 v2
v3 v4
v5
v6
v7
v8
x1
x4
x3
nodes send random linear combinations
every message – linear equation
v1 v2
v3 v4
v5
v6
v7
v8
x1+ 2x3
+ 7x4= 250
3x1 + 4x4 =134
4x2+ x4
+ 8x3= 730
nodes send random linear combinations
every message – linear equation
v1 v2
v3 v4
v5
v6
v7
v8
x1+ 2x3
+ 7x4= 250
3x1 + 4x4 =134
4x2+ x4
+ 8x3= 730
nodes store equations in a matrix form:
1 0 2 72 0 0 71 1 0 00 0 0 0
·
x1x2x3x4
=
25045780
nodes store equations in a matrix form:
1 0 2 72 0 0 71 1 0 00 0 0 0
·
x1x2x3x4
=
25045780
120
random coefficients ∈ Fq
1× 1x1 + 0x2 + 2x3 + 7x4 = 250
2× 2x1 + 0x2 + 0x3 + 7x4 = 45
5x1 + 0x2 + 2x3 + 21x4 = 340
rank k – node finishesonly helpful
messages are stored
Algebraic Gossip
3/12
instead of sending randomly chosen values...
every message – a single value
v1 v2
v3 v4
v5
v6
v7
v8
x1
x4
x3
nodes send random linear combinations
every message – linear equation
v1 v2
v3 v4
v5
v6
v7
v8
x1+ 2x3
+ 7x4= 250
3x1 + 4x4 =134
4x2+ x4
+ 8x3= 730
nodes send random linear combinations
every message – linear equation
v1 v2
v3 v4
v5
v6
v7
v8
x1+ 2x3
+ 7x4= 250
3x1 + 4x4 =134
4x2+ x4
+ 8x3= 730
nodes store equations in a matrix form:
1 0 2 72 0 0 71 1 0 00 0 0 0
·
x1x2x3x4
=
25045780
nodes store equations in a matrix form:
1 0 2 72 0 0 71 1 0 00 0 0 0
·
x1x2x3x4
=
25045780
120
random coefficients ∈ Fq
1× 1x1 + 0x2 + 2x3 + 7x4 = 250
2× 2x1 + 0x2 + 0x3 + 7x4 = 45
5x1 + 0x2 + 2x3 + 21x4 = 340
rank k – node finishesonly helpful
messages are stored
Algebraic Gossip
3/12
instead of sending randomly chosen values...
every message – a single value
v1 v2
v3 v4
v5
v6
v7
v8
x1
x4
x3
nodes send random linear combinations
every message – linear equation
v1 v2
v3 v4
v5
v6
v7
v8
x1+ 2x3
+ 7x4= 250
3x1 + 4x4 =134
4x2+ x4
+ 8x3= 730
nodes send random linear combinations
every message – linear equation
v1 v2
v3 v4
v5
v6
v7
v8
x1+ 2x3
+ 7x4= 250
3x1 + 4x4 =134
4x2+ x4
+ 8x3= 730
nodes store equations in a matrix form:
1 0 2 72 0 0 71 1 0 00 0 0 0
·
x1x2x3x4
=
25045780
nodes store equations in a matrix form:
1 0 2 72 0 0 71 1 0 00 0 0 0
·
x1x2x3x4
=
25045780
120
random coefficients ∈ Fq
1× 1x1 + 0x2 + 2x3 + 7x4 = 250
2× 2x1 + 0x2 + 0x3 + 7x4 = 45
5x1 + 0x2 + 2x3 + 21x4 = 340
rank k – node finishesonly helpful
messages are stored
Algebraic Gossip
3/12
instead of sending randomly chosen values...
every message – a single value
v1 v2
v3 v4
v5
v6
v7
v8
x1
x4
x3
nodes send random linear combinations
every message – linear equation
v1 v2
v3 v4
v5
v6
v7
v8
x1+ 2x3
+ 7x4= 250
3x1 + 4x4 =134
4x2+ x4
+ 8x3= 730
nodes send random linear combinations
every message – linear equation
v1 v2
v3 v4
v5
v6
v7
v8
x1+ 2x3
+ 7x4= 250
3x1 + 4x4 =134
4x2+ x4
+ 8x3= 730
nodes store equations in a matrix form:
1 0 2 72 0 0 71 1 0 00 0 0 0
·
x1x2x3x4
=
25045780
nodes store equations in a matrix form:
1 0 2 72 0 0 71 1 0 00 0 0 0
·
x1x2x3x4
=
25045780
120
random coefficients ∈ Fq
1× 1x1 + 0x2 + 2x3 + 7x4 = 250
2× 2x1 + 0x2 + 0x3 + 7x4 = 45
5x1 + 0x2 + 2x3 + 21x4 = 340
rank k – node finishesonly helpful
messages are stored
Algebraic Gossip
3/12
instead of sending randomly chosen values...
every message – a single value
v1 v2
v3 v4
v5
v6
v7
v8
x1
x4
x3
nodes send random linear combinations
every message – linear equation
v1 v2
v3 v4
v5
v6
v7
v8
x1+ 2x3
+ 7x4= 250
3x1 + 4x4 =134
4x2+ x4
+ 8x3= 730
nodes send random linear combinations
every message – linear equation
v1 v2
v3 v4
v5
v6
v7
v8
x1+ 2x3
+ 7x4= 250
3x1 + 4x4 =134
4x2+ x4
+ 8x3= 730
nodes store equations in a matrix form:
1 0 2 72 0 0 71 1 0 00 0 0 0
·
x1x2x3x4
=
25045780
nodes store equations in a matrix form:
1 0 2 72 0 0 71 1 0 00 0 0 0
·
x1x2x3x4
=
25045780
120
random coefficients ∈ Fq
1× 1x1 + 0x2 + 2x3 + 7x4 = 250
2× 2x1 + 0x2 + 0x3 + 7x4 = 45
5x1 + 0x2 + 2x3 + 21x4 = 340
rank k – node finishesonly helpful
messages are stored
So, Why Algebraic Gossip is Faster?
4/12
A B
Pr (helpful) = 1k
[x1, x2, x3, . . . xk ] [x1, x2=?, x3, . . . xk ]
Without Algebraic Gossip (Random Message Selection)
A has all values B is missing one valueA sends a random message
A B
Pr (helpful) = 1k
[x1, x2, x3, . . . xk ] [x1, x2=?, x3, . . . xk ]
Without Algebraic Gossip (Random Message Selection)
A has all values B is missing one valueA sends a random message
A B
Pr (helpful) = 1 − 1q
rank k
rank k − 1
With Algebraic Gossip (Random Linear Equations)
k indep. equations k − 1 indep. equationsA sends a random linear equation
qk−qk−1
qk = 1− 1q
So, Why Algebraic Gossip is Faster?
4/12
A B
Pr (helpful) = 1k
[x1, x2, x3, . . . xk ] [x1, x2=?, x3, . . . xk ]
Without Algebraic Gossip (Random Message Selection)
A has all values B is missing one valueA sends a random message
A B
Pr (helpful) = 1k
[x1, x2, x3, . . . xk ] [x1, x2=?, x3, . . . xk ]
Without Algebraic Gossip (Random Message Selection)
A has all values B is missing one valueA sends a random message
A B
Pr (helpful) = 1 − 1q
rank k
rank k − 1
With Algebraic Gossip (Random Linear Equations)
k indep. equations k − 1 indep. equationsA sends a random linear equation
qk−qk−1
qk = 1− 1q
Research Goal
5/12
v1 v2
v3 v4
v5
v6
v7
v8
x1 = 5 x2 = 15
x3 = 10 x4 = 12k -Disseminationproblem
Analyze uniformalgebraic gossip
is itoptimal?
for whichgraphs?
Study non-uniformalgebraic gossip
we propose treebased algebraic gossip
Research Goal
5/12
v1 v2
v3 v4
v5
v6
v7
v8
x1 = 5 x2 = 15
x3 = 10 x4 = 12k -Disseminationproblem
Analyze uniformalgebraic gossip
is itoptimal?
for whichgraphs?
Study non-uniformalgebraic gossip
we propose treebased algebraic gossip
Related Work
[Deb et al., 2006] – complete graphFor k ln3 n : Tight bound – Θ(k).
[Mosk-Aoyama and Shah, 2006] – any graph, k = nNot tight bound.
[Borokhovich et al., 2010] – k = nUpper bound – O(∆n) for any graph.Tight bound – Θ(n) for constant max degree graphs.
[Haeupler, 2010] – any graphFor k = Ω(n) : Tight bound – Θ(n/γ).For k < o(n) : Not tight for: line, grid, binary tree, ...
6/12
k -Dissemination with uniform algebraic gossip
Related Work
[Deb et al., 2006] – complete graphFor k ln3 n : Tight bound – Θ(k).
[Mosk-Aoyama and Shah, 2006] – any graph, k = nNot tight bound.
[Borokhovich et al., 2010] – k = nUpper bound – O(∆n) for any graph.Tight bound – Θ(n) for constant max degree graphs.
[Haeupler, 2010] – any graphFor k = Ω(n) : Tight bound – Θ(n/γ).For k < o(n) : Not tight for: line, grid, binary tree, ...
6/12
k -Dissemination with uniform algebraic gossip
Related Work
[Deb et al., 2006] – complete graphFor k ln3 n : Tight bound – Θ(k).
[Mosk-Aoyama and Shah, 2006] – any graph, k = nNot tight bound.
[Borokhovich et al., 2010] – k = nUpper bound – O(∆n) for any graph.Tight bound – Θ(n) for constant max degree graphs.
[Haeupler, 2010] – any graphFor k = Ω(n) : Tight bound – Θ(n/γ).For k < o(n) : Not tight for: line, grid, binary tree, ...
6/12
k -Dissemination with uniform algebraic gossip
Related Work
[Deb et al., 2006] – complete graphFor k ln3 n : Tight bound – Θ(k).
[Mosk-Aoyama and Shah, 2006] – any graph, k = nNot tight bound.
[Borokhovich et al., 2010] – k = nUpper bound – O(∆n) for any graph.Tight bound – Θ(n) for constant max degree graphs.
[Haeupler, 2010] – any graphFor k = Ω(n) : Tight bound – Θ(n/γ).For k < o(n) : Not tight for: line, grid, binary tree, ...
6/12
k -Dissemination with uniform algebraic gossip
Results
7/12
two main results
1st Result
7/12
k -Dissemination
Uniform algebraic gossip
Any graph
O(∆(k + log n + D))
max degree diameter
Const max degree graphs
Θ(k + D)
Optimal!
Results hold for
push, pull, exch
Barbell graph
Ω(nk)
Bad!
v
u
1st Result
7/12
k -Dissemination
Uniform algebraic gossip
Any graph
O(∆(k + log n + D))
max degree diameter
Const max degree graphs
Θ(k + D)
Optimal!
Results hold for
push, pull, exch
Barbell graph
Ω(nk)
Bad!
v
u
1st Result
7/12
k -Dissemination
Uniform algebraic gossip
Any graph
O(∆(k + log n + D))
max degree diameter
Const max degree graphs
Θ(k + D)
Optimal!
Results hold for
push, pull, exch
Barbell graph
Ω(nk)
Bad!
v
u
1st Result
7/12
k -Dissemination
Uniform algebraic gossip
Any graph
O(∆(k + log n + D))
max degree diameter
Const max degree graphs
Θ(k + D)
Optimal!
Results hold for
push, pull, exch
Barbell graph
Ω(nk)
Bad!
v
u
1st Result
7/12
k -Dissemination
Uniform algebraic gossip
Any graph
O(∆(k + log n + D))
max degree diameter
Const max degree graphs
Θ(k + D)
Optimal!
Results hold for
push, pull, exch
Barbell graph
Ω(nk)
Bad!
v
u
2nd Result
8/12
k -Dissemination
Tree based algebraic gossip
v1 v2
v3 v4
v5
v6
v7
v8 v1 v2
v3 v4
v5
v6
v7
v8
Phase 1Span tree algo S
Phase
2
Algebraic gossiponly with parent
t(S)
O(∆(k + log n + D)
O(t(S)+k +log n+d(S))
Any graph, k = Ω(n)
Θ(n)
Optimal!
2nd Result
8/12
k -Dissemination
Tree based algebraic gossip
v1 v2
v3 v4
v5
v6
v7
v8
v1 v2
v3 v4
v5
v6
v7
v8
Phase 1Span tree algo S
Phase
2
Algebraic gossiponly with parent
t(S)
O(∆(k + log n + D)
O(t(S)+k +log n+d(S))
Any graph, k = Ω(n)
Θ(n)
Optimal!
2nd Result
8/12
k -Dissemination
Tree based algebraic gossip
v1 v2
v3 v4
v5
v6
v7
v8 v1 v2
v3 v4
v5
v6
v7
v8
Phase 1Span tree algo S
Phase
2
Algebraic gossiponly with parent
t(S)
O(∆(k + log n + D)
O(t(S)+k +log n+d(S))
Any graph, k = Ω(n)
Θ(n)
Optimal!
2nd Result
8/12
k -Dissemination
Tree based algebraic gossip
v1 v2
v3 v4
v5
v6
v7
v8 v1 v2
v3 v4
v5
v6
v7
v8
Phase 1Span tree algo S
Phase
2
Algebraic gossiponly with parent
t(S)
O(∆(k + log n + D)
O(t(S)+k +log n+d(S))
Any graph, k = Ω(n)
Θ(n)
Optimal!
2nd Result
8/12
k -Dissemination
Tree based algebraic gossip
v1 v2
v3 v4
v5
v6
v7
v8 v1 v2
v3 v4
v5
v6
v7
v8
Phase 1Span tree algo S
Phase
2
Algebraic gossiponly with parent
t(S)
O(∆(k + log n + D)
O(t(S)+k +log n+d(S))
Any graph, k = Ω(n)
Θ(n)
Optimal!
Proof Overview
9/12
k -Dissemination with uniform algebraic gossip
O(∆(k + log n + D))
Converting a Graph to a System of Queues
9/12
v1 v2
v3 v4
v5
v6
v7
v8
x1 x2
x3 x4
x5
x6
v1 v2
v3 v4
v5
v6
v7
v8
p ≥?
x1 x2
x3 x4
x5
x6
v1 v2
v3 v4
v5
v6
v7
v8
p ≥ 1∆
x1 x2
x3 x4
x5
x6
v1 v2
v3 v4
v5
v6
v7
v8
p ≥ 1∆ (1 − 1
q )
x1 x2
x3 x4
x5
x6
initial graph with an arbitrary node v4
when v4 will finish the protocol?
v1 v2
v3 v4
v5
v6
v7
v8
x1 x2
x3
x4
x5
x6
BFS spanning tree rooted at v4
we ignore the messages coming from other edges
v1 v2
v3 v4
v5
v6
v7
v8
x1 x2
x3
x4
x5
x6
customers are helpful messages
customers increase node’s rank
a node need k helpful messages to finish
v5 chooses v6 w.p. ≥ 1∆
message is helpful w.p. ≥ (1 − 1q )
service time is ∼ Geom(p)
Converting a Graph to a System of Queues
9/12
v1 v2
v3 v4
v5
v6
v7
v8
x1 x2
x3 x4
x5
x6
v1 v2
v3 v4
v5
v6
v7
v8
p ≥?
x1 x2
x3 x4
x5
x6
v1 v2
v3 v4
v5
v6
v7
v8
p ≥ 1∆
x1 x2
x3 x4
x5
x6
v1 v2
v3 v4
v5
v6
v7
v8
p ≥ 1∆ (1 − 1
q )
x1 x2
x3 x4
x5
x6
initial graph with an arbitrary node v4
when v4 will finish the protocol?
v1 v2
v3 v4
v5
v6
v7
v8
x1 x2
x3
x4
x5
x6
BFS spanning tree rooted at v4
we ignore the messages coming from other edges
v1 v2
v3 v4
v5
v6
v7
v8
x1 x2
x3
x4
x5
x6
customers are helpful messages
customers increase node’s rank
a node need k helpful messages to finish
v5 chooses v6 w.p. ≥ 1∆
message is helpful w.p. ≥ (1 − 1q )
service time is ∼ Geom(p)
Converting a Graph to a System of Queues
9/12
v1 v2
v3 v4
v5
v6
v7
v8
x1 x2
x3 x4
x5
x6
v1 v2
v3 v4
v5
v6
v7
v8
p ≥?
x1 x2
x3 x4
x5
x6
v1 v2
v3 v4
v5
v6
v7
v8
p ≥ 1∆
x1 x2
x3 x4
x5
x6
v1 v2
v3 v4
v5
v6
v7
v8
p ≥ 1∆ (1 − 1
q )
x1 x2
x3 x4
x5
x6
initial graph with an arbitrary node v4
when v4 will finish the protocol?
v1 v2
v3 v4
v5
v6
v7
v8
x1 x2
x3
x4
x5
x6
BFS spanning tree rooted at v4
we ignore the messages coming from other edges
v1 v2
v3 v4
v5
v6
v7
v8
x1 x2
x3
x4
x5
x6
customers are helpful messages
customers increase node’s rank
a node need k helpful messages to finish
v5 chooses v6 w.p. ≥ 1∆
message is helpful w.p. ≥ (1 − 1q )
service time is ∼ Geom(p)
Converting a Graph to a System of Queues
9/12
v1 v2
v3 v4
v5
v6
v7
v8
x1 x2
x3 x4
x5
x6
v1 v2
v3 v4
v5
v6
v7
v8
p ≥?
x1 x2
x3 x4
x5
x6
v1 v2
v3 v4
v5
v6
v7
v8
p ≥ 1∆
x1 x2
x3 x4
x5
x6
v1 v2
v3 v4
v5
v6
v7
v8
p ≥ 1∆ (1 − 1
q )
x1 x2
x3 x4
x5
x6
initial graph with an arbitrary node v4
when v4 will finish the protocol?
v1 v2
v3 v4
v5
v6
v7
v8
x1 x2
x3
x4
x5
x6
BFS spanning tree rooted at v4
we ignore the messages coming from other edges
v1 v2
v3 v4
v5
v6
v7
v8
x1 x2
x3
x4
x5
x6
customers are helpful messages
customers increase node’s rank
a node need k helpful messages to finish
v5 chooses v6 w.p. ≥ 1∆
message is helpful w.p. ≥ (1 − 1q )
service time is ∼ Geom(p)
Converting a Graph to a System of Queues
9/12
v1 v2
v3 v4
v5
v6
v7
v8
x1 x2
x3 x4
x5
x6
v1 v2
v3 v4
v5
v6
v7
v8
p ≥?
x1 x2
x3 x4
x5
x6
v1 v2
v3 v4
v5
v6
v7
v8
p ≥ 1∆
x1 x2
x3 x4
x5
x6
v1 v2
v3 v4
v5
v6
v7
v8
p ≥ 1∆ (1 − 1
q )
x1 x2
x3 x4
x5
x6
initial graph with an arbitrary node v4
when v4 will finish the protocol?
v1 v2
v3 v4
v5
v6
v7
v8
x1 x2
x3
x4
x5
x6
BFS spanning tree rooted at v4
we ignore the messages coming from other edges
v1 v2
v3 v4
v5
v6
v7
v8
x1 x2
x3
x4
x5
x6
customers are helpful messages
customers increase node’s rank
a node need k helpful messages to finish
v5 chooses v6 w.p. ≥ 1∆
message is helpful w.p. ≥ (1 − 1q )
service time is ∼ Geom(p)
Converting a Graph to a System of Queues
9/12
v1 v2
v3 v4
v5
v6
v7
v8
x1 x2
x3 x4
x5
x6
v1 v2
v3 v4
v5
v6
v7
v8
p ≥?
x1 x2
x3 x4
x5
x6
v1 v2
v3 v4
v5
v6
v7
v8
p ≥ 1∆
x1 x2
x3 x4
x5
x6
v1 v2
v3 v4
v5
v6
v7
v8
p ≥ 1∆ (1 − 1
q )
x1 x2
x3 x4
x5
x6
initial graph with an arbitrary node v4
when v4 will finish the protocol?
v1 v2
v3 v4
v5
v6
v7
v8
x1 x2
x3
x4
x5
x6
BFS spanning tree rooted at v4
we ignore the messages coming from other edges
v1 v2
v3 v4
v5
v6
v7
v8
x1 x2
x3
x4
x5
x6
customers are helpful messages
customers increase node’s rank
a node need k helpful messages to finish
v5 chooses v6 w.p. ≥ 1∆
message is helpful w.p. ≥ (1 − 1q )
service time is ∼ Geom(p)
Exponential Servers Instead of Geometric
10/12
v1 v2
v3 v4
v5
v6
v7
v8
p
p
p
p
p
p
p
v1 v2
v3 v4
v5
v6
v7
v8
µ
µ
µ
µ
µ
µ
µ
µ = p
If X ∼ Geom(p), and Y ∼ Exp(p), then: Pr(Y > t) ≥ Pr(X > t)
exponential server is slower than geometric
we replace servers, thus increasing the stopping time
Exponential Servers Instead of Geometric
10/12
v1 v2
v3 v4
v5
v6
v7
v8
p
p
p
p
p
p
p
v1 v2
v3 v4
v5
v6
v7
v8
µ
µ
µ
µ
µ
µ
µ
µ = p
If X ∼ Geom(p), and Y ∼ Exp(p), then: Pr(Y > t) ≥ Pr(X > t)
exponential server is slower than geometric
we replace servers, thus increasing the stopping time
Line is Slower Than Tree
11/12
v1 v2
v3 v4
v5
v6
v7
v8
µ
µ
µ
µ
µ
µ
µ
v4µ µ µ
v4µ µ µλ = µ
2 v4µ µ µλ = µ
2
When does the
last customer
leave the system?
Reduce tree to line
Take all customers out and use Jackson theorem
Inter-arrival time ∼Exp( µ2 )
All arrive after O((k + log n)/µ)
Time to cross MM1 ∼Exp( µ2 )
Time to cross D queues O((D + log n)/µ)
Total: O((k + log n + D)/µ) = O(∆(k + log n + D)) rounds
Line is Slower Than Tree
11/12
v1 v2
v3 v4
v5
v6
v7
v8
µ
µ
µ
µ
µ
µ
µ
v4µ µ µ
v4µ µ µλ = µ
2 v4µ µ µλ = µ
2
When does the
last customer
leave the system?
Reduce tree to line
Take all customers out and use Jackson theorem
Inter-arrival time ∼Exp( µ2 )
All arrive after O((k + log n)/µ)
Time to cross MM1 ∼Exp( µ2 )
Time to cross D queues O((D + log n)/µ)
Total: O((k + log n + D)/µ) = O(∆(k + log n + D)) rounds
Line is Slower Than Tree
11/12
v1 v2
v3 v4
v5
v6
v7
v8
µ
µ
µ
µ
µ
µ
µ
v4µ µ µ
v4µ µ µλ = µ
2
v4µ µ µλ = µ
2
When does the
last customer
leave the system?
Reduce tree to line
Take all customers out and use Jackson theorem
Inter-arrival time ∼Exp( µ2 )
All arrive after O((k + log n)/µ)
Time to cross MM1 ∼Exp( µ2 )
Time to cross D queues O((D + log n)/µ)
Total: O((k + log n + D)/µ) = O(∆(k + log n + D)) rounds
Line is Slower Than Tree
11/12
v1 v2
v3 v4
v5
v6
v7
v8
µ
µ
µ
µ
µ
µ
µ
v4µ µ µ
v4µ µ µλ = µ
2
v4µ µ µλ = µ
2
When does the
last customer
leave the system?
Reduce tree to line
Take all customers out and use Jackson theorem
Inter-arrival time ∼Exp( µ2 )
All arrive after O((k + log n)/µ)
Time to cross MM1 ∼Exp( µ2 )
Time to cross D queues O((D + log n)/µ)
Total: O((k + log n + D)/µ) = O(∆(k + log n + D)) rounds
Line is Slower Than Tree
11/12
v1 v2
v3 v4
v5
v6
v7
v8
µ
µ
µ
µ
µ
µ
µ
v4µ µ µ
v4µ µ µλ = µ
2
v4µ µ µλ = µ
2
When does the
last customer
leave the system?
Reduce tree to line
Take all customers out and use Jackson theorem
Inter-arrival time ∼Exp( µ2 )
All arrive after O((k + log n)/µ)
Time to cross MM1 ∼Exp( µ2 )
Time to cross D queues O((D + log n)/µ)
Total: O((k + log n + D)/µ) = O(∆(k + log n + D)) rounds
Line is Slower Than Tree
11/12
v1 v2
v3 v4
v5
v6
v7
v8
µ
µ
µ
µ
µ
µ
µ
v4µ µ µ
v4µ µ µλ = µ
2
v4µ µ µλ = µ
2
When does the
last customer
leave the system?
Reduce tree to line
Take all customers out and use Jackson theorem
Inter-arrival time ∼Exp( µ2 )
All arrive after O((k + log n)/µ)
Time to cross MM1 ∼Exp( µ2 )
Time to cross D queues O((D + log n)/µ)
Total: O((k + log n + D)/µ) = O(∆(k + log n + D)) rounds
Line is Slower Than Tree
11/12
v1 v2
v3 v4
v5
v6
v7
v8
µ
µ
µ
µ
µ
µ
µ
v4µ µ µ
v4µ µ µλ = µ
2
v4µ µ µλ = µ
2
When does the
last customer
leave the system?
Reduce tree to line
Take all customers out and use Jackson theorem
Inter-arrival time ∼Exp( µ2 )
All arrive after O((k + log n)/µ)
Time to cross MM1 ∼Exp( µ2 )
Time to cross D queues O((D + log n)/µ)
Total: O((k + log n + D)/µ) = O(∆(k + log n + D)) rounds
Summary
12/12
k -Dissemination problem
Uniform algebraic gossip Tree based algebraic gossip
Any graph
O(∆(k + log n + D))
Const max degree graphs
Θ(k + D)Optim
al!
Any graph
O(t(S) + k + log n + d(S))
Any graph, k = Ω(n)
Θ(n)Optim
al!
Open questions
Optimal cases What S to use?
THANK YOU!
Summary
12/12
k -Dissemination problem
Uniform algebraic gossip Tree based algebraic gossip
Any graph
O(∆(k + log n + D))
Const max degree graphs
Θ(k + D)Optim
al!
Any graph
O(t(S) + k + log n + d(S))
Any graph, k = Ω(n)
Θ(n)Optim
al!
Open questions
Optimal cases What S to use?
THANK YOU!
Summary
12/12
k -Dissemination problem
Uniform algebraic gossip Tree based algebraic gossip
Any graph
O(∆(k + log n + D))
Const max degree graphs
Θ(k + D)Optim
al!
Any graph
O(t(S) + k + log n + d(S))
Any graph, k = Ω(n)
Θ(n)Optim
al!
Open questions
Optimal cases What S to use?
THANK YOU!
Summary
12/12
k -Dissemination problem
Uniform algebraic gossip Tree based algebraic gossip
Any graph
O(∆(k + log n + D))
Const max degree graphs
Θ(k + D)Optim
al!
Any graph
O(t(S) + k + log n + d(S))
Any graph, k = Ω(n)
Θ(n)Optim
al!
Open questions
Optimal cases What S to use?
THANK YOU!
Summary
12/12
k -Dissemination problem
Uniform algebraic gossip Tree based algebraic gossip
Any graph
O(∆(k + log n + D))
Const max degree graphs
Θ(k + D)Optim
al!
Any graph
O(t(S) + k + log n + d(S))
Any graph, k = Ω(n)
Θ(n)Optim
al!
Open questions
Optimal cases What S to use?
THANK YOU!
Summary
12/12
k -Dissemination problem
Uniform algebraic gossip Tree based algebraic gossip
Any graph
O(∆(k + log n + D))
Const max degree graphs
Θ(k + D)Optim
al!
Any graph
O(t(S) + k + log n + d(S))
Any graph, k = Ω(n)
Θ(n)Optim
al!
Open questions
Optimal cases What S to use?
THANK YOU!
Summary
12/12
k -Dissemination problem
Uniform algebraic gossip Tree based algebraic gossip
Any graph
O(∆(k + log n + D))
Const max degree graphs
Θ(k + D)Optim
al!
Any graph
O(t(S) + k + log n + d(S))
Any graph, k = Ω(n)
Θ(n)Optim
al!
Open questions
Optimal cases What S to use?
THANK YOU!
Algebraic Gossip – Overhead?
12/12
1,0,2,7 | 250
x1 + 2x3 + 7x4 = 250
ai ∈ Fq∑
aixi ∈ Frq
Initial value size: r log q bits.
Overhead (coefficients): k log q bits.
Bits efficiency: r log qk log q+r log q = r
k+r → 1.
nodes store equations in a matrix form:
1 0 2 72 0 0 41 1 0 00 2 1 5
·
x1x2x3x4
=
2504578308
ai ∈ Fq xi ∈ Frq
∑aixi ∈ Fr
q
Algebraic Gossip – Overhead?
12/12
1,0,2,7 | 250
x1 + 2x3 + 7x4 = 250
ai ∈ Fq∑
aixi ∈ Frq
Initial value size: r log q bits.
Overhead (coefficients): k log q bits.
Bits efficiency: r log qk log q+r log q = r
k+r → 1.
nodes store equations in a matrix form:
1 0 2 72 0 0 41 1 0 00 2 1 5
·
x1x2x3x4
=
2504578308
ai ∈ Fq xi ∈ Frq
∑aixi ∈ Fr
q
Algebraic Gossip – Example
12/12
v1
v2 v3
x1 = a
x3 = cx2 = b
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
325
random coefficients
0,2,0 | 2b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
562
random coefficients
5,12,0 | 5a + 12b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
436
random coefficients
20,48,6 | 20a + 48b + 6c
v1
v2 v3
1 0 00 2 0
20 48 6
·
x1x2x3
=
a2b
20a + 48b + 6c
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
⇒x1 = ax2 = bx3 = c
Algebraic Gossip – Example
12/12
v1
v2 v3
x1 = a
x3 = cx2 = b
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
325
random coefficients
0,2,0 | 2b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
562
random coefficients
5,12,0 | 5a + 12b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
436
random coefficients
20,48,6 | 20a + 48b + 6c
v1
v2 v3
1 0 00 2 0
20 48 6
·
x1x2x3
=
a2b
20a + 48b + 6c
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
⇒x1 = ax2 = bx3 = c
Algebraic Gossip – Example
12/12
v1
v2 v3
x1 = a
x3 = cx2 = b
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
325
random coefficients
0,2,0 | 2b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
562
random coefficients
5,12,0 | 5a + 12b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
436
random coefficients
20,48,6 | 20a + 48b + 6c
v1
v2 v3
1 0 00 2 0
20 48 6
·
x1x2x3
=
a2b
20a + 48b + 6c
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
⇒x1 = ax2 = bx3 = c
Algebraic Gossip – Example
12/12
v1
v2 v3
x1 = a
x3 = cx2 = b
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
325
random coefficients
0,2,0 | 2b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
562
random coefficients
5,12,0 | 5a + 12b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
436
random coefficients
20,48,6 | 20a + 48b + 6c
v1
v2 v3
1 0 00 2 0
20 48 6
·
x1x2x3
=
a2b
20a + 48b + 6c
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
⇒x1 = ax2 = bx3 = c
Algebraic Gossip – Example
12/12
v1
v2 v3
x1 = a
x3 = cx2 = b
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
325
random coefficients
0,2,0 | 2b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
562
random coefficients
5,12,0 | 5a + 12b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
436
random coefficients
20,48,6 | 20a + 48b + 6c
v1
v2 v3
1 0 00 2 0
20 48 6
·
x1x2x3
=
a2b
20a + 48b + 6c
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
⇒x1 = ax2 = bx3 = c
Algebraic Gossip – Example
12/12
v1
v2 v3
x1 = a
x3 = cx2 = b
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
325
random coefficients
0,2,0 | 2b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
562
random coefficients
5,12,0 | 5a + 12b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
436
random coefficients
20,48,6 | 20a + 48b + 6c
v1
v2 v3
1 0 00 2 0
20 48 6
·
x1x2x3
=
a2b
20a + 48b + 6c
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
⇒x1 = ax2 = bx3 = c
Algebraic Gossip – Example
12/12
v1
v2 v3
x1 = a
x3 = cx2 = b
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
325
random coefficients
0,2,0 | 2b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
562
random coefficients
5,12,0 | 5a + 12b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
436
random coefficients
20,48,6 | 20a + 48b + 6c
v1
v2 v3
1 0 00 2 0
20 48 6
·
x1x2x3
=
a2b
20a + 48b + 6c
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
⇒x1 = ax2 = bx3 = c
Algebraic Gossip – Example
12/12
v1
v2 v3
x1 = a
x3 = cx2 = b
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
325
random coefficients
0,2,0 | 2b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
562
random coefficients
5,12,0 | 5a + 12b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
436
random coefficients
20,48,6 | 20a + 48b + 6c
v1
v2 v3
1 0 00 2 0
20 48 6
·
x1x2x3
=
a2b
20a + 48b + 6c
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
⇒x1 = ax2 = bx3 = c
Algebraic Gossip – Example
12/12
v1
v2 v3
x1 = a
x3 = cx2 = b
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
325
random coefficients
0,2,0 | 2b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
562
random coefficients
5,12,0 | 5a + 12b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
436
random coefficients
20,48,6 | 20a + 48b + 6c
v1
v2 v3
1 0 00 2 0
20 48 6
·
x1x2x3
=
a2b
20a + 48b + 6c
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
⇒x1 = ax2 = bx3 = c
Algebraic Gossip – Example
12/12
v1
v2 v3
x1 = a
x3 = cx2 = b
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 0 00 0 0
·
x1x2x3
=
a00
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
325
random coefficients
0,2,0 | 2b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
0 0 00 0 00 0 1
·
x1x2x3
=
00c
562
random coefficients
5,12,0 | 5a + 12b
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
v1
v2 v3
1 0 00 2 00 0 0
·
x1x2x3
=
a2b0
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
436
random coefficients
20,48,6 | 20a + 48b + 6c
v1
v2 v3
1 0 00 2 0
20 48 6
·
x1x2x3
=
a2b
20a + 48b + 6c
0 0 00 1 00 0 0
·
x1x2x3
=
0b0
5 12 00 0 00 0 1
·
x1x2x3
=
5a + 12b0c
⇒x1 = ax2 = bx3 = c
Borokhovich, M., Avin, C., and Lotker, Z. (2010).Tight bounds for algebraic gossip on graphs.In 2010 IEEE International Symposium on InformationTheory Proceedings (ISIT), pages 1758 –1762.
Deb, S., Médard, M., and Choute, C. (2006).Algebraic gossip: a network coding approach to optimalmultiple rumor mongering.IEEE Transactions on Information Theory,52(6):2486–2507.
Haeupler, B. (2010).Analyzing Network Coding Gossip Made Easy.To appear in the 43rd ACM Symposium on Theory ofComputing (STOC), 2011.
Mosk-Aoyama, D. and Shah, D. (2006).Information dissemination via network coding.In ISIT, pages 1748–1752.
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