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dguhath
Posts: 61
Posted 12:15 Aug 28, 2015 |

Question-1

PPT 8 slide 50 states:

"mnbrs have same ref level with r = 1 and oid = i (Case Detect):"
 
Now in slide 69, C receives update from both A & B. And both A & B have the same reference level, i.e 1, E, 1; with r = 1;
In this case C does a propagate in slide 70. 
So can we add another condition that states :
"mnbrs have same ref level with r = 1 and oid  not = i =>Case Propagate & adopt r = 1"
 
Question-2
 
Also in slide 69 A's values are: "1, E, 1, -2, A" Should σ be 0 here as it is a case of reflection?
 
Or can we casually say, σ will adopt the value in case of reflection & decrease the value in case of propagation?
 
Last edited by dguhath at 12:15 Aug 28, 2015.
raylongma1018
Posts: 81
Posted 13:02 Aug 28, 2015 |

i believe on question 1 In this case, it is the case reflect but not case detect. The reason is because when c receives the reflection link from a and b where sigma equal to 1, e;s r is still 0. That means c still not receiving reflection link from e yet. unless c receives all the reflection link from all its neighbor it won't have case detect. one of trick to know case detect happen is when there is partition. We can easily see if there is partition or not by looking at the graph and see if there is no connection between two sets of nodes.

for question 2 

sigma becomes 0 when case reflect happens but that 0 can mean reference to the previous node where it sends the reversal link. as we can see from the lecture slide and homework, at the time a node receives reversal link from all its neighbors and it will have full reversal for refection link, the r value is the same value from the last node which send the reversal link. 

I believe you can still set r equal 0 because from slide 55 they example set the r to 0, but another example from slide 69 and solution from the homework are using another way.

 

dguhath
Posts: 61
Posted 14:57 Aug 28, 2015 |

Thanks for your reply.

 

For Qs-1,

I understand the whole partition thing. The point that I am trying to make here is there is a missing case.

I agree to what u said on the partition thing but I disagree to - "it is the case reflect but not case detect." as it is a case propagate according to slide 70.

So the question still remains - Can we say:

"mnbrs have same ref level with r = 1 and oid  not = i =>Case Propagate & adopt r = 1"

 

For Qs-2, I guess you got confused with the parameter r here. I did not refer to that.

My question is on σ, the 4th parameter and it's values under different circumstances.

raylongma1018
Posts: 81
Posted 00:40 Aug 29, 2015 |

for question1 

I would say it is case reflect. here is the reason. at slide 69 between a and c there are two links one is r=0 (reversal link)and one is r=1 (reflection link)and there are also two links between b and c r=0, 1(reversal , refection link); and there is a link between e and c r= 0 (reversal link)since c's link to all its neigbors has reversal linke r=0 so it is considered as case reflect. it's not case propogate, because all c's link has been reversed before, so it won't consider as case propogate. 

for question2 

if you look at the cases between slide 55 and slide 69 and homework 2 problems, the example from slide 55 it turns the 4th parameter sigma into 0 when a node has case reflect, but if you look at case for slide 69 and homework2 it does not turn the 4th parameter sigma to 0 instead it has the same value of the node which gives reversal link. I believe both cases are fine but I　will stick with one from the homework. 

dguhath
Posts: 61
Posted 11:15 Aug 29, 2015 |

For Qs-1,

I am sorry but i did not get your point.

It cannot be a reflect as in case of a reflect all incident links get reversed. But if you see slide 70 only the CE link gets reversed. Which is how propagate works.

For Qs-2,

I just wanted to confirm which of the 2 possible ways should we adopt. Or it really doesn't matter.

raylongma1018
Posts: 81
Posted 12:52 Aug 29, 2015 |

for q1

ce link has been reversed, but ac and bc has also been reversed. although ac and bc link at that point is reflect, but it can't change the fact that ac, bc link has been reversed before. since ac, bc, and ce link all has been reversed before. c will have case reflect

for q2 

I believe it's best to stick with the one with the solution of homework. 

dguhath
Posts: 61
Posted 14:11 Aug 29, 2015 |

if c has a case reflect, the diagram in slide 70 is incorrect. Is that what you mean?

i guess you understand that reflection = full reversal

& propagation = partial reversal

Last edited by dguhath at 14:14 Aug 29, 2015.
raylongma1018
Posts: 81
Posted 19:09 Aug 29, 2015 |

for question1 

now i get your point

i think it's case propogate and it propogate a reverse link c-e from c to e.