ATAR Notes: Forum

VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE General & Further Mathematics => Topic started by: Yendall on October 18, 2012, 11:13:13 pm

Title: Networks Frustration
Post by: Yendall on October 18, 2012, 11:13:13 pm

(http://i292.photobucket.com/albums/mm37/yendall_2008/networks_zps31e5d1e0.jpg)

This question is asking for the capacity of the cut. To my knowledge, a cut is to stop all flows from the source to the sink. So any cut that is running toward the sink is a potential flow that needs to be cut. In this diagram, are not all those edges running through the cut, going toward the sink?

(http://i292.photobucket.com/albums/mm37/yendall_2008/networks2_zps6ed788ad.jpg)

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VCAA's answer is that one of the edges weighted '4' is not flowing toward the sink and should not be included in the cut calculation. From my perspective, aren't both those edges running directly to the sink? 

Title: Re: Networks Frustration
Post by: Daenerys Targaryen on October 19, 2012, 04:15:02 pm

The 4 towards the middle is moving inwards to the cut.
The node that the '4' is moving towards lies within the side of the source.

Title: Re: Networks Frustration
Post by: lukaal340 on October 19, 2012, 04:29:34 pm

It has to go from the source side of the cut, to the sink side. The edge weighted 4 starts on the sink side and ends on the source side, so it is not included in the cuts capacity.

Title: Re: Networks Frustration
Post by: Yendall on October 20, 2012, 04:40:06 pm

Oh okay I get it now. Thanks guys