Input: DSDG, DR

Output: CDS

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function DSComposition(DSDG, DR)

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 fields ← DR

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  for each field in fields do

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  ADSs ← ADS related to field

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  end for

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 InitQueue(queue)

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  EnQueue(queue, ADS ₀)     ▷The first ADS of ADSs

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  while!QueueEmpty(queue) do

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  ADS _i ← DeQueue(queue)

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  adj_ADSs ← DSDG  ▷Find all adjacent ADSs of ADS _i

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   for each ADS in adj_ADSs do

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    ifADS haven’t been visited then

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    EnQueue(queue, ADS)

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    pre_ADSs ← ADS _i is the prior node of ADS

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     if all ADSs have been visited then

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     break;

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     end if

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    end if

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   end for

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  end while

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  for j = 1 → the size of ADSs do

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  cur_ADS ← ADS _j

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  pre_ADS ← pre_ADSs(cur_ADS)     ▷Get the prior node of cur ADS

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   while cur ADS is not ADS ₁ do

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    if CDS dosen’t contain cur_ADS then

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    Add cur_ADS into CDS;

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    else

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    break

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    end if

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   cur ADS ← pre ADS

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   pre ADS ← pre ADSs(cur ADS)

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   end while

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  end for

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  return CDS

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end function