When talking about SAT solvers, of the like of minisat for example, what does the value of "0-depth" and "CNF assignments" mean? These values are usually part of the information output of various SAT solvers.
A zero depth assignment is setting a variable's value before DPLL search has begun. The preprocessing of the formula that MiniSAT does (subsumption, self subsumption, etc.) can sometimes prove that a variable must have a certain value. If it can MiniSAT will fix the value of such variables before beginning the DPLL procedure.
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I'm using TF-Agents library for reinforcement learning,
and I would like to take into account that, for a given state,
some actions are invalid.
How can this be implemented?
Should I define a "observation_and_action_constraint_splitter" function when
creating the DqnAgent?
If yes: do you know any tutorial on this?
Yes you need to define the function, pass it to the agent and also appropriately change the environment output so that the function can work with it. I am not aware on any tutorials on this, however you can look at this repo I have been working on.
Note that it is very messy and a lot of the files in there actually are not being used and the docstrings are terrible and often wrong (I forked this and didn't bother to sort everything out). However it is definetly working correctly. The parts that are relevant to your question are:
rl_env.py in the HanabiEnv.__init__ where the _observation_spec is defined as a dictionary of ArraySpecs (here). You can ignore game_obs, hand_obs and knowledge_obs which are used to run the environment verbosely, they are not fed to the agent.
rl_env.py in the HanabiEnv._reset at line 110 gives an idea of how the timestep observations are constructed and returned from the environment. legal_moves are passed through a np.logical_not since my specific environment marks legal_moves with 0 and illegal ones with -inf; whilst TF-Agents expects a 1/True for a legal move. My vector when cast to bool would therefore result in the exact opposite of what it should be for TF-agents.
These observations will then be fed to the observation_and_action_constraint_splitter in utility.py (here) where a tuple containing the observations and the action constraints is returned. Note that game_obs, hand_obs and knowledge_obs are implicitly thrown away (and not fed to the agent as previosuly mentioned.
Finally this observation_and_action_constraint_splitter is fed to the agent in utility.py in the create_agent function at line 198 for example.
I'm having trouble understanding the rfc5545 concerning the the until and count. From what I understand, UNTIL and COUNT cannot be in the same recur rule according to this part of the RFC:
Value Name: RECUR
Purpose: This value type is used to identify properties that
contain a recurrence rule specification.
Formal Definition: The value type is defined by the following
notation:
recur = "FREQ"=freq *(
; either UNTIL or COUNT may appear in a 'recur',
; but UNTIL and COUNT MUST NOT occur in the same 'recur'
...
Further in the rfc, this is stated:
If multiple BYxxx rule parts are specified, then after evaluating the
specified FREQ and INTERVAL rule parts, the BYxxx rule parts are
applied to the current set of evaluated occurrences in the following
order: BYMONTH, BYWEEKNO, BYYEARDAY, BYMONTHDAY, BYDAY, BYHOUR,
BYMINUTE, BYSECOND and BYSETPOS; then COUNT and UNTIL are evaluated.
This last paragraph seems to imply that the COUNT and UNTIL can be in the same RRULE.
When I check libraries that implement rrule generator and parsing, there is no validation that make sure that the the COUNT and UNTIL are not in the same recur.
What is the general implementation that everyone usually do with this ? Should we ignore this validation and simply use the UNTIL parameter when there is both COUNT and UNTIL (or vice versa) ? What does the RFC mean exactly concerning the COUNT and UNTIL parameter ?
I don't think you can derive from the second paragraph that having both is valid.
There is only one definition of RECUR and the cardinality of its various components: the ABNF definition. This is where you should go to check the validity of your property.
The second paragraph simply describes the algorithm to use for doing RRULE expansion.
I am trying to write a code in Netlogo with which it can apply the next equation:
The equation represent the change of Se value (the number of a breed of turtles), the constant kse is a parameter value defined by a slider, the next value is another parameter defined by a slider and the summatory part, is the sum of the operation of the parentesis which is: each sj (that is a turtle-own variable) less the total of the breed population (Se)
The problem is with the summatory part because i really dont know how to write it. I though, made an ask procedure defining each variable with the "let" command but it give me wrong results, so i am thinking doing it with a report procedure but i really dont know how to write it.
Supposes the breed is esses and the turtle attribute is s, then
let _Se count esses
let _sum [s - _Se] of esses
Note: if this is really meant to govern the change in the number of turtles (as you indicate in your question), you will have to decide what to do with non-integer outcomes.
I'm working with legacy code and ran across something that I haven't been able to explain after several days of looking up tutorials and handbooks for GW Basic: a variable (P9%) is used in a comparison on line 530 (IF P9% <> 0) before the code would reach its definition on line 860. It's not a complex piece of code, only ~1200 lines total, so I am confident that I haven't missed any goto or gosub or anything that would reach 860 earlier than this comparison.
I am curious as to how this has been effecting the program as it runs. Most of my experience is with c++ where this sort of thing wouldn't compile, and if it did an unassigned variable could potentially contain anything that would fit, but I have no idea what kind of default assignment is given to a variable in Basic.
It has been many years since I wrote much in gwbasic!
If I remember correctly the variable is assigned a zero value in that case. Gwbasic (and Qbasic I think) assigns a default value to all variables when first referenced, this is usually zero or the empty string for a string variable.
Interestingly when creating an array using the DIM statement, all the items in the array are also initialised this way.
Even with this mechanism it is usually better to initialise a variable, just to be clear what is happening.
Many programmers of the era writing for gwbasic omitted as much as they could to minimise the amount of memory used by the program instructions so they had more for other stuff. So that may be why it's not initialised.
In algebra if I make the statement x + y = 3, the variables I used will hold the values either 2 and 1 or 1 and 2. I know that assignment in programming is not the same thing, but I got to wondering. If I wanted to represent the value of, say, a quantumly weird particle, I would want my variable to have two values at the same time and to have it resolve into one or the other later. Or maybe I'm just dreaming?
Is it possible to say something like i = 3 or 2;?
This is one of the features planned for Perl 6 (junctions), with syntax that should look like my $a = 1|2|3;
If ever implemented, it would work intuitively, like $a==1 being true at the same time as $a==2. Also, for example, $a+1 would give you a value of 2|3|4.
This feature is actually available in Perl5 as well through Perl6::Junction and Quantum::Superpositions modules, but without the syntax sugar (through 'functions' all and any).
At least for comparison (b < any(1,2,3)) it was also available in Microsoft Cω experimental language, however it was not documented anywhere (I just tried it when I was looking at Cω and it just worked).
You can't do this with native types, but there's nothing stopping you from creating a variable object (presuming you are using an OO language) which has a range of values or even a probability density function rather than an actual value.
You will also need to define all the mathematical operators between your variables and your variables and native scalars. Same goes for the equality and assignment operators.
numpy arrays do something similar for vectors and matrices.
That's also the kind of thing you can do in Prolog. You define rules that constraint your variables and then let Prolog resolve them ...
It takes some time to get used to it, but it is wonderful for certain problems once you know how to use it ...
Damien Conways Quantum::Superpositions might do what you want,
https://metacpan.org/pod/Quantum::Superpositions
You might need your crack-pipe however.
What you're asking seems to be how to implement a Fuzzy Logic system. These have been around for some time and you can undoubtedly pick up a library for the common programming languages quite easily.
You could use a struct and handle the operations manualy. Otherwise, no a variable only has 1 value at a time.
A variable is nothing more than an address into memory. That means a variable describes exactly one place in memory (length depending on the type). So as long as we have no "quantum memory" (and we dont have it, and it doesnt look like we will have it in near future), the answer is a NO.
If you want to program and to modell this behaviour, your way would be to use a an array (with length equal to the number of max. multiple values). With this comes the increased runtime, hence the computations must be done on each of the values (e.g. x+y, must compute with 2 different values x1+y1, x2+y2, x1+y2 and x2+y1).
In Perl , you can .
If you use Scalar::Util , you can have a var take 2 values . One if it's used in string context , and another if it's used in a numerical context .