# [r-t] q-sets

Philip Earis pje24 at cantab.net
Wed Jul 30 13:36:56 UTC 2008

```Tom Willis:
"Given I keep on seeing references to q-sets, does anyone have a handy
link which explains them in more detail?"

It seems nobody is prepared to stick their head above the parapet...

Tom, if you haven't done so already I suggest you read the paper "The
Mathematics of Change Ringing", which is available online at:

<http://www.masa.on.net/The%20Mathematics%20of%20Change%20Ringing.pdf>

Someone like Richard Smith will be able to give you a formal mathematical
definition. However, for a rough-and-ready everyday use version, a q-set
is a set of calls affecting the same bells.

The terminology "q-set" is often used when talking about extents. For
example, the standard (WHW)*3 extent of minor can be thought of as just
having a call whenever bells 2&6, 3&6 or 4&6 are dodging together at the
back (ie unaffected by the bob).  Thus you can think of 2&6, 3&6 and 4&6

When composing something like a plain minor method, if you just
consistently put bobs in affecting the same q-sets then you'll get a true
touch.

For 4ths place bobs, there are three bobs in each set (ie a touch with
three calls in the same place, eg 3 homes, will get you back where you
started).

So you'll also sometimes hear q-sets mentioned when people are talking
about eg compositions of surprise maximus.

Take a look at the following neat (but musically terrible!) composition of
Yokrshire Maximus by Peter Border:

23456    M   W   H
45236        -   -
53246        2
43265    s   s   3
63245        s
52436    s   -   2
(32456)       s

After the first single middle, single wrong the calls basically just
cancel each other out (complete the q-set). ie the three homes cancel each
other out, then the next single wrong cancels out the previous single
wrong, etc.  What you're left with it the simple touch W, SW.

Simon Linford gave a worked example of Yorkshire Major along similar lines
in his recent RW article. I also think Steve Coleman talks a bit about
q-sets in one of his books.

Hope this helps - ask if anything is unclear.

```