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+label_prop(1) -- Find communities using label propagation
+======
+
+## SYNOPSIS
+
+`label_prop` [SYNC|ASYNC] <graph_in> [<max_epochs>]
+
+## DESCRIPTION
+
+`label_prop` finds the communities in <graph_in> using the label
+propagation algorithm proposed by Raghavan, Albert, and Kumara. The
+program prints on STDOUT the partition obtained where no more label
+flips are possible, and reports on STDERR the number of communities
+and the corresponding value of modularity at each epoch. When used in
+ASYNC mode, the algorithm is suitable to find communities in large
+graphs.
+
+## PARAMETERS
+
+* `SYNC`|`ASYNC`:
+    The first parameter is used to choose between synchronous (`SYNC`)
+    or asynchronous (`ASYNC`) label update. 
+
+* <graph_in>:
+    undirected input graph (edge list). If is equal to `-` (dash), read
+    the edge list from STDIN.
+    
+* <max_epochs>:
+    Sets the maximum number of epochs to run (optional).
+
+## OUTPUT
+
+The program prints on STDOUT the partition obtained where no more
+label flips are possible, in the format:
+
+        ## nc: NUM_COMM Q_max: Q_MAX Epochs: EPOCHS
+        node_1 comm_1
+        node_2 comm_2
+        node_3 comm_3
+        ... 
+        
+where `comm_i` is the community to which `node_i` belongs. The first
+output line reports the number of communities `NUM_COMM`,  the
+corresponding value of modularity `Q_MAX`, and the number of epochs
+`EPOCHS` used to find the partition.
+
+The program prints on STDERR the epoch number, the value of modularity
+of the partition at that epoch, and the number of flips made in that
+epoch, in the format:
+
+        1 Q_1 flips_1
+        2 Q_2 flips_2
+        3 Q_3 flips_3
+        ....
+
+where `Q_i` is the modularity of the partition at the i-th epoch, and
+`flips_i` is the number of label flips performed during that
+epoch. 
+
+## EXAMPLES
+
+We can use `label_prop` to find communities in the graph
+`karate_club_unweighted.net` (Zachary Karate Club network) with the command:
+
+        $ label_prop ASYNC karate_club_unweighted.net 2> karate_label-prop_trace
+        ### nc: 2 Q_max: 0.371795 Epochs: 6
+        0 0
+        1 0
+        2 0
+        3 0
+        ...
+        30 1
+        31 1
+        32 1
+        33 1
+        $ 
+        
+The program has found a partition with 2 communities corrisponding to
+a modularity Q=0.371795. Notice that node 0, 1, 2, 3, are in community
+0, while node 30, 31, 32, 33 are in community 1.  In this example, we
+have chosen to save the information about the modularity and number of
+flips at each epoch in the file `karate_label-prop_trace`.
+
+## SEE ALSO
+
+modularity(1), gn(1), cnm(1)
+
+## REFERENCES
+
+* U\. N. Raghavan, R. Albert, and S. Kumara. "Near linear time
+  algorithm to detect community structures in large-scale
+  networks". Phys. Rev. E 76 (2007), 036106.
+
+* V\. Latora, V. Nicosia, G. Russo, "Complex Networks: Principles,
+  Methods and Applications", Appendix 19, Cambridge University Press
+  (2017)
+
+* V\. Latora, V. Nicosia, G. Russo, "Complex Networks: Principles,
+  Methods and Applications", Chapter 9, Cambridge University Press
+  (2017)
+
+## AUTHORS
+
+(c) Vincenzo 'KatolaZ' Nicosia 2009-2017 `<v.nicosia@qmul.ac.uk>`.