changed default of num_cores to 0 (system decides, see tf doc)

experiment.py

@@ -41,7 +41,7 @@ def run_config_params():
     seed = 1406182976
     run_params = dict(
             master=None,
-            num_cores=3,
+            num_cores=0,  # If 0, the system picks an appropriate number (default: 0)
             log_device_placement=False,
             gpu_memory_fraction=0.75,
             tf_random_seed=seed,