Merge pull request #46 from Gurobi/Marika-K-patch-1

fix typo in tsp.ipynb

traveling_salesman/tsp.ipynb

@@ -32,7 +32,7 @@
     "\n",
     "In the early 1970s, the concept of P vs. NP problems created excitement in the theoretical computer science community. In 1972, Richard Karp demonstrated that the Hamiltonian cycle problem was NP-complete, implying that the traveling salesman problem was NP-hard.\n",
     "\n",
-    "Increasingly sophisticated codes led to rapid increases in the sizes of the traveling salesman problems solved. Dantzig, Fulkerson, and Johnson had solved a 48-city instance of the problem in 1954. Martin Grötechel more than doubled this 23 years later, solving a 120-city instance in 1977. Harlan Crowder and Manfred W. Padberg again more than doubled this in just 3 years, with a 318-city solution.\n",
+    "Increasingly sophisticated codes led to rapid increases in the sizes of the traveling salesman problems solved. Dantzig, Fulkerson, and Johnson had solved a 48-city instance of the problem in 1954. Martin Grötschel more than doubled this 23 years later, solving a 120-city instance in 1977. Harlan Crowder and Manfred W. Padberg again more than doubled this in just 3 years, with a 318-city solution.\n",
     "\n",
     "In 1987, rapid improvements were made, culminating in a 2,392-city solution by Padberg and Giovanni Rinaldi. In the following two decades, great strides were made with David L. Applegate, Robert E. Bixby, Vasek Chvátal, & William J. Cook solving a 3,308-city instance in 1992, a 7,397-city instance in 1994, a 24,978-city instance in 2004, and an 85,900-city instance in 2006 – which is the largest 2-D Euclidean TSP instance ever solved. William Cook et. al. wrote a program called Concorde TSP Solver for solving the TSP [4]. Concorde is a computer code for the symmetric TSP and some related network optimization problems. The code is written in the ANSI C programming language and it has been used to obtain the optimal solutions to the full set of 110 TSPLIB instances, the largest instance is a 109,399 node 3-D “star” instance.\n",
     "\n",