Consider the sequence (7,7,7,6,6,4,4,3). (a) perform the reduction operation repeatedly until a sequence con- taining negative numbers appears. (b) is the sequene obtained graphic? why/why not? use the theorem to determine whether the original sequence is graphic or not. (c) assume, for some graph, the repeated reduction operation produces the sequence (2) or (4,0). is either of these graphic? what can you conclude about the original sequence?