diff --git a/examples/6_constraint_solve/main.c b/examples/6_constraint_solve/main.c
index dfb5fff5279fd85a2ca37fe175d5d60fceb516b4..6084ffd933f6ca9beb1a665ce80787868127bdde 100644
--- a/examples/6_constraint_solve/main.c
+++ b/examples/6_constraint_solve/main.c
@@ -1,65 +1,103 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <time.h>
+#include <assert.h>
 #include "../../reowolf.h"
 #include "../utility.c"
 
+#define N 4
+
+typedef struct PeerInfo {
+	int id;
+	bool puts; // true iff the channel to this peer is INCOMING.
+} PeerInfo;
+
+// return the index of (i,j) in the lexicographic ordering of set {(i,j) : i<j, j<N}
+// for convenience, swaps (i,j) if i>j 
+int combination_index(int i, int j) {
+	if (i > j) {
+		// swap!
+		i ^= j;
+		j ^= i;
+		i ^= j;
+	}
+	assert(0 <= i);
+	assert(i < j);
+	assert(j < N);
+		
+	int idx_in_square = i*N + j;
+	int skipped = ((i+1) * (i+2)) / 2;
+	return idx_in_square - skipped;
+}
+
+// initializes the given 3-element array,
+// breaking symmetry with put-get direction.
+void init_peer_infos(PeerInfo * peer_infos, int my_id) {
+	int i;
+	for (i = 0; i < 3; i++) {
+		PeerInfo * pi = &peer_infos[i];
+		pi->puts = i < my_id;
+		pi->id = i < my_id ? i : i+1;
+		printf("info %d puts=%d id=%d\n", i, pi->puts, pi->id);
+	}
+}
+
+const char* addrs[] = {
+	"127.0.0.1:7000",
+	"127.0.0.1:7001",
+	"127.0.0.1:7002",
+	"127.0.0.1:7003",
+	"127.0.0.1:7004",
+	"127.0.0.1:7005",
+};
 int main(int arg_c, char * argv[]) {
-	int index;
+	int my_id, peer_id, i;
 	if (arg_c != 2) {
 		printf("Expected one arg: which peer I am in 0..4");
 		return 1;
 	}
-	index = atoi(argv[1]);
-	printf("I am peer %d\n", index);
+	my_id = atoi(argv[1]);
+	assert(0 <= my_id && my_id < N);
+	printf("I have id %d\n", my_id);
 	
-	const char* addrs[] = {
-		"127.0.0.1:7000",
-		"127.0.0.1:7001",
-		"127.0.0.1:7002",
-		"127.0.0.1:7003",
-		"127.0.0.1:7004",
-		"127.0.0.1:7005",
-	};
-
 	char * pdl = buffer_pdl("eg_protocols.pdl");
 	
 	Connector* c = connector_new();
 	printf("configuring...\n");
-
 	check("config ", connector_configure(c, pdl, "xor_three"));
-	int i, j;
-	int addr_index = 0;
-	int port = 0;
-	for (i = 0; i < 4; i++) {
-		for (j = i+1; j < 4; j++) {
-			if (i==index) {
-				printf("ports %d and %d are for a passive channel to peer %d over addr %s\n", port, port+1, j, addrs[addr_index]);
-				check("bind an ", connector_bind_native(c, port));
-				port++;
-				check("bind a  ", connector_bind_active(c, port, addrs[addr_index]));
-				port++;
-			} else if (j==index) {
-				printf("ports %d and %d are for an active channel to peer %d over addr %s\n", port, port+1, i, addrs[addr_index]);
-				check("bind p  ", connector_bind_passive(c, port, addrs[addr_index]));
-				port++;
-				check("bind pn ", connector_bind_native(c, port));
-				port++;
-			}
-			addr_index++;
+	
+	PeerInfo peer_infos[3];
+	init_peer_infos(peer_infos, my_id);
+	
+	// for every native port, bind native and protocol port.
+	for (i = 0; i < 3; i++) {
+		PeerInfo * pi = &peer_infos[i];
+		int addr_idx = combination_index(my_id, pi->id);
+		if (pi->puts) {
+			check("bind to putter ",
+				connector_bind_passive(c, i*2, addrs[addr_idx]));
+			check("bind native ", connector_bind_native(c, i*2 + 1));
+		} else {
+			check("bind native ", connector_bind_native(c, i*2));
+			check("bind to putter ",
+				connector_bind_active(c, i*2 + 1, addrs[addr_idx]));
 		}
 	}
+	printf("connecting...\n");
 	check("connect", connector_connect(c, 5000));
 	
-	for (i = 0; i < 4; i++) {
-		if (i == index) continue;
-		// another batch
-		for (j = 0; j < 4; j++) {
-			
-		}
+	// for every native port, create a singleton batch
+	for (i = 0; i < 3; i++) {
+		if (i > 0) check("next ", connector_next_batch(c));
+		PeerInfo * pi = &peer_infos[i];
+		check("op ", pi->puts?
+			connector_get(c, i):
+			connector_put(c, i, NULL, 0));
 	}
-	connector_sync();
+	// solve!
+	int batch_idx = connector_sync(c, 3000);
+	if (batch_idx < 0) printf("Error code on sync! %d\n", batch_idx);
+	else printf("I was paired with peer %d\n", peer_infos[batch_idx].id);
 	
 	printf("destroying...\n");
 	connector_destroy(c);