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1 of 8 0-day streak

Determine and certify maximum flow

Question 1 of 8

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Consider the directed network for a server-request network. The source is W and the sink is Y. Each edge label is its capacity in requests/s. The network transfers requests each second; intermediate vertices pass on all incoming flow

Use inspection to allocate a feasible flow before checking its upper bound

Directed capacity network. Source W; sink Y. Full edge list: W→D1 capacity 20 requests/s; D1→H capacity 40 requests/s; H→O capacity 50 requests/s; O→Y capacity 30 requests/s; W→F1 capacity 50 requests/s; F1→Y capacity 80 requests/s; W→I capacity 50 requests/s; I→E1 capacity 80 requests/s; E1→Y capacity 60 requests/s.204050305080508060WYD1HOF1IE1

The table specifies one particular feasible-flow certificate, not every possible feasible flow. Keep each displayed flow fixed and determine only the question-mark entries using conservation. Flow and capacity use the same units shown above. The diagram labels are capacities, not assigned flows

Partially specified feasible-flow certificate. A question mark is an unknown, not zero
Directed edgeCapacityAssigned flow
W→D12020
D1→H4020
H→O5020
O→Y3020
W→F150?
F1→Y8050
W→I50?
I→E18050
E1→Y6050
(a)2 marks

Enter the selected edge flows so that the displayed allocation is feasible

(b)1 mark

What is the greatest feasible flow from source W to sink Y?