fixes

posts/2017-01-17-lazy-io-graphs.lhs

@@ -124,7 +124,9 @@ CREATE INDEX roads_origin ON roads (origin);
 [sqlite]: http://sqlite.org/
 
 The road costs have been generated by multiplying the actual distances with a
-random number uniformly chosen between `0.6` and `1.4`.
+random number uniformly chosen between `0.6` and `1.4`.  Cities have been
+(bidirectionally) connected to at least four closest neighbours.  This ensures
+that every city is reachable.
 
 You can load this database by issueing:
 
@@ -140,7 +142,7 @@ We can use a `let` to create bindings that refer to one another easily.
 > test01 = do
 >     let winterfell = City "wtf" "Winterfell" (-105, 78)
 >           [(13, moatCailin), (12, whiteHarbor)]
->         whiteHarbor = City "wih" "White Hardbor" (-96, 74)
+>         whiteHarbor = City "wih" "White Harbor" (-96, 74)
 >           [(15, braavos), (12, winterfell)]
 >         moatCailin = City "mtc" "Moat Cailin" (-104, 72)
 >           [(20, crossroads), (13, winterfell)]