053: Graceful Graphs

language ESSENCE' 1.0

$written by Karen E. J. Petrie,  5th of Sept, 2015

find nodes : matrix indexed by [int(1..8)] of int(0..16)
find edges : matrix indexed by [int(1..16)] of int(1..16)
     
such that
	|nodes[1] - nodes[2]| = edges[1],
	|nodes[1] - nodes[3]| = edges[2],
	|nodes[1] - nodes[4]| = edges[3],
	|nodes[2] - nodes[3]| = edges[4],
	|nodes[2] - nodes[4]| = edges[5],
	|nodes[3] - nodes[4]| = edges[6],
	|nodes[5] - nodes[6]| = edges[7],
	|nodes[5] - nodes[7]| = edges[8],
	|nodes[5] - nodes[8]| = edges[9],
	|nodes[6] - nodes[7]| = edges[10],
	|nodes[6] - nodes[8]| = edges[11],
	|nodes[7] - nodes[8]| = edges[12],
	|nodes[1] - nodes[5]| = edges[13],
	|nodes[2] - nodes[6]| = edges[14],
	|nodes[3] - nodes[7]| = edges[15],
	|nodes[4] - nodes[8]| = edges[16],
	alldifferent(edges),
	alldifferent(nodes)