BFACF Basic Help

load... button:
Click on this button to bring up a panel of choices of knots to load.  The knots with a `c'
in their name are composite knots.  Here is a table of what they correspond to:
       6c_1   3_1#3_1
       6c_1s  3_1s#3_1s
       6c_2   3_1#3_1s
       7c_1   3_1#4_1
       7c_1s  3_1s#4_1
       8c_1   3_1#5_1
       8c_1s  3_1s#5_1s
       8c_2   3_1s#5_1
       8c_2s  3_1#5_1s
       8c_3   3_1#5_2
       8c_3s  3_1s#5_2s
       8c_4   3_1s#5_2
       8c_4s  3_1#5_2s
       8c_5   4_1#4_1


link open obstacle obstacle2 buttons:
Simple examples of what can be done with multi-component links, open-ended components and 
freezing a component to make into a topological obstruction of some kind.
 
centre on/off buttons:
Recall that knots, especially small ones, tend to wander off and are no longer visible in the 
view window. click on "centre on" to keep them centered in the view window. This is only a 
display option, it doesn't affect the simulation.  The buttons are equivalent to the commands:
bfacf centre on
bfacf centre off

freeze/thaw buttons:
Optionally freeze or thaw one or more components. 

embed button:
Use this button to embed a smooth knot or two component link into the simple cubic lattice. 
Doesn't always work, and you have to check that the knot type doesn't change.  If the command 
reports that the "Current position is safe" and the min max max/min and aver lengths are 1.000,
then you're probably OK.  Sometimes you may have to scale the knot (use the `scale' command, 
see the manual).  You can make new cubic lattice knots, for example try the command sequence:
load 5.2
load sum 7.5
and then click on the `embed' button. If you get what looks like a nice knot, click the button:

bfacf load button:
Loads a knot sitting in the KnotPlot Arena into the BFACF engine.  Equivalent to the command
bfacf load
KnotPlot will complain if it doesn't like what you're trying to load.  Only knots with one or
two components may be loaded into the BFACF engine. 

Simulation method: 
You have the choice of two (soon three) simulation methods, BFACF and KJC (kink jump crankshaft).
BFACF is ergodic and KJC isn't. However, KJC is length preserving and "ergodic enough" for some us,
at least for long, loose knots. If you are using the KJC method, the z and p() sliders have no 
meaning.

Plot:
Simulation needs to be running to see the plot update. If the plot is inappropriately scaled, try
changing the scale with a command something like:
plot scale 1.08
plot scale 3
(default is a scale of 1)

set probs:
These are convenience buttons to automatically set the probabilities. The "from z" button sets the 
probabilities according to the standard formula. "0 only" is equivalent to the KnotPlot command
bfacf prob 0 1 0
and reduce equivalent to
bfacf prob 0 1 1

p(+2) p(0) p(-2) sliders:
Set the probabilities for the different BFACF moves for your own crazy interests.  Useful for the
minimal stick search, or to get very long knots. 

z sliders:
First slider goes from z=0 to z=0.208 (the critical value), giving you finer control over this
range. The other slider is from z=0 to z=1.  Changing these slider values will automatically set
the probabilities according to the formula.  To set a specific value for z, either use type it into
the KnotPlot Command Window, for example:
bfacf z .108
or double click on the value field in the slider. 

