Re: Filtering a list of list for certain elements that are neighbours

*To*: mathgroup at smc.vnet.net*Subject*: [mg88855] Re: Filtering a list of list for certain elements that are neighbours*From*: Szabolcs Horvát <szhorvat at gmail.com>*Date*: Mon, 19 May 2008 05:17:56 -0400 (EDT)*Organization*: University of Bergen*References*: <g0p4a2$nc4$1@smc.vnet.net>

Steven Siew wrote: > I have a list of lists > > mylist={{a,b,c},{a,c,b},{b,a,c},{b,c,a},{c,a,b},{c,b,a}} > > I want to filter out all lists that have "a being a neighbor to b". > > I am looking for the following result. > > {{a,c,b},{b,c,a}} > > > For this toy example, I can probably do it by hand but my real problem > has 120 lists in a list. And I need to filter out various combination > of letters like "s cannot be next to d" , "s cannot be next to j" , "c > cannot be next to j" , "h cannot be next to d" and "h cannot be next > to s". > Cases[mylist, Except[{___, a, b, ___} | {___, b, a, ___}]]