# Flip-flop **URL:** \ **Category:** CSG2017\ **Created:** [October 21, 2017, 2:16pm UTC](http://discourse.iapct.org/t/flip-flop/4454 "2017-10-21T14:16:03Z")\ **Posts on this page:** 1\ **Showing post:** 15

**Author:** ![MartinT](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/m/ee7513/32.png) [@MartinT](http://discourse.iapct.org/u/MartinT)\ **Post date:** [December 20, 2017, 7:10pm UTC](http://discourse.iapct.org/t/flip-flop/4454/15 "2017-12-20T19:10:04Z")

[Martin Taylor 2017.12.20.13.29] > [From Rupert Young (2017.12.20 18.15)] > (Martin Taylor 2017.12.19.12.01] > > > > [From Rupert Young (2017.12.19 16.05)] > > > > > > ``` > > > (Martin Taylor 2017.11.23.11.30] > > > > > > ``` > > > > > > > ``` > > > > Here's a spreadsheet that implements a > > > > > > > > ``` > > > > > > > > two-way flip-flop. It’s not very elegant, and it may be > > > > buggy, but it seems to work. I expect you could easily > > > > improve on it in various ways, or make a one-way one (i.e. > > > > with values never below zero). > > > > > > ``` > > > This appears to show a B output of > 1 even though B input > > > > > > ``` > > > > > > is zero. In that case shouldn’t B output always be zero? > > > > ``` > > No. You have two inputs into each perceiver, the input from > > > > ``` > > > > below (which I call the “input”) and the feedback input from the > > other output. So long as the feedback input is strong enough, it > > doesn’t matter what the input from below does, the flip-flop > > will maintain the same output high and the other zero. If Aout > > has been high, it will stay high until Bin-Ain\>some > > threshold. At least that’s what it is supposed to do, if my > > spreadsheet programming is correct, which is far from > > guaranteed. > > ``` > Well, it seems strange that even though Bin is zero this would > > ``` > > provide a category of B. Are you sure that is what it is supposed > to do? ``` It is exactly what a flip-flop is supposed to do. I explained in my ``` previous message why the simple flip-flop is unlikely to be what you want as a category recognizer. It is a category discriminator, without a third “none-of-the-above” output. In words, it is 100% certain that either A or B is true but not both, and the question is which one it is. If Bout is positive when Bin is zero, that is because Bin is greater than Ain, or if at this moment it is not, it has been up to now and the excess of Ain is as yet insufficient to say that things have changed. > ``` > Here's my replication of your spreadsheet model. Initially B is > > ``` > > suppressed such that it is -ve. Initially A is +ve, but when it > goes -ve it then increases Bsum due to the -ve weight. Perhaps > Bsum should not go above zero if Bin is zero? ``` No. That is exactly what it is supposed to do. ``` > ![fjjijneepcihcknf.png](http://discourse.iapct.org/uploads/default/original/1X/e79b718ceb72bbbc55f29f522e0117b062614cec.png) > > > > ``` > > > How does this work if B input is not > > > > > > ``` > > > > > > zero, and has a different phase to A, and sometimes A=B? For > > > the latter shouldn’t only one output be non-zero? > > > > ``` > > Yes, except for the transition period while the flip is > > > > ``` > > > > flopping. When A=B, whichever one was previously high stays high > > until the imbalance of the inputs is sufficient to overwhelm the > > cross-feedback loop effect, Then you have several samples of a > > transient condition (in the analogue system that could be > > pico-seconds, seconds, minutes, or years) while both are > > non-zero until the flop is complete. In the spreadsheet, I used > > a leaky integrator to smooth the transient. Without looking back > > at the spreadsheet, I forget the leak rate, but it had to have a > > time-constant of several samples. > > ``` > That's not what I am finding here. B has the same value as A, > > ``` > > albeit briefly. ``` Your diagrams show that it is what you find in your replication, ``` exactly what I said. During the transition period, both are briefly positive, and there has to be a moment when both have the same positive value. > ``` > ![njnmaeeoekkpfmok.png|1392x900](upload://zM3CYMhTFbqdlZo5NyTK3PluqY9.png) > > In practice the model doesn't appear to be as straightforward as > > ``` > > the theory would seem to suggest, ``` Well, so far, it seems to be working in a very straightforward ``` manner as the theory says it should. What problem do you still see? ``` Do you want me to produce a polyflop demo instead? I was going to do ``` that, but I have to figure out how to program something like subroutines in Excel so I don’t have to deal with thousands of lines of the data for each sample moment and can simply produce graphs for the inputs and outputs. Probably Excel isn’t the best language to use, but I just wanted to show something quick and dirty that works as intended. I can’t spend much time on programming a polyflop, as I am spending most my time on PPC. A proper polyflop simulation probably needs a parallel programming structure anyway, and that’s a bit beyond me. Maybe a randomized order of updating per sample would do. I don’t know, but it could be worth a try. > ``` > so I don't think I can spare any more time on this myself. > > ``` > > However, if you are able to revisit the model I’d be very > interested to see that it can work. ``` You have that now. I suspect that the problem is that you were ``` looking for a circuit that is supposed to do something different. You want to suppress the category output if there’s no analogue variable to be categorized. If the flip-flop discriminates between “Lion” and “Tiger” you want it to be inhibited if the analogue perception of both are less than some threshold. It shouldn’t be too hard to add an inhibitory connection based on the sum of Ain and Bin. You might want to do that in a practical robot, but it’s simple enough that I don’t think it’s worth doing as an addition to this working simulation. However, as always I may change my mind tomorrow. ``` Martin ``` > **···** > > > ``` > > Rupert > > > > ``` --- _[View the full topic](http://discourse.iapct.org/t/flip-flop/4454)._