In the context of bounded model checking, one describes the system as a State Transition System and the properties that need to be checked.
When one needs to provide multiple system descriptions and properties to the Model Checker Tool, it can become tedious to write the property by hand. In my case, I use some temporal logic.
How does one automate the process of translating/parsing the system description and deriving verifiable properties from it (ideally, a set of Initial states, Transitions, Set of States).
For example, consider the Microwave Example given here Given such a system description, how can I arrive at the specifications in an efficient manner?
There is no such open source tool that I know of, that can do this. Any approaches in terms of ideas, theories are welcome.
You can't automatically derive LTL formulae from automata as you suggest, because automata are more expressive than LTL formulae.
That leaves you with mainly two options: 1. find a verification tool which accepts specifications that are directly expressed as automata (I'm not sure which ones do, but I suspect it is worth checking SPIN and NuSMV for this feature.), or 2. use a meta-specification language that makes the writing of specifications easier; for example, https://www.isp.uni-luebeck.de/salt (doi: 10.1007/11901433_41) or IEE1850/PSL. While PSL is more a language definition for tool-implementors, SALT already offers a web front-end that translates your input straight into LTL.
(By the way, I find your approach methodologically challenging though: you're not supposed to derive formulae from your model, but from your initial system description as it is this very model which you're going to verify. But I am not a 100% sure, if I understood this point in your question correctly.)
I think properties of a system, e.g. Microwave system, come from technical and common sense expectation and requirements, not the model. E.g. microwave is supposed to cook the food. But it is not supposed to cook with door open. Nevertheless a repository of typical LTL pattern can be useful to define properties. It also lists properties along with more familiar regex and automata properties.
If you certain you still want to translate automata to LTL automatically check
https://mathoverflow.net/questions/96963/translate-a-buchi-automaton-to-ltl
Kansas Specification Property Repository
http://patterns.projects.cs.ksu.edu/documentation/patterns.shtml
Related
It's common to add a custom dictionary to a machine translator to ensure that terminology from a specific domain is correctly translated. For example, the term server should be translated differently when the document is about data centers, vs when the document is about restaurants.
With a transformer model, this is not very obvious to do, since words are not aligned 1:1. I've seen a couple of papers on this topic, but I'm not sure which would be the best one to use. What are the best practices for this problem?
I am afraid you cannot easily do that. You cannot easily add new words to the vocabulary because you don't know what embedding it would get during training. You can try to remove some words, or alternatively you can manually change the bias in the final softmax layer to prevent some words from appearing in the translation. Anything else would be pretty difficult to do.
What you want to do is called domain adaptation. To get an idea of how domain adaptation is usually done, you can have a look at a survey paper.
The most commonly used approaches are probably model finetuning or ensembling with a language model. If you want to have parallel data in your domain, you can try to fine-tune your model on that parallel data (with simple SGD, small learning rate).
If you only have monolingual data in the target language, you train a language model on that data. During the decoding, you can mix the probabilities from the domain-specific language and the translation model. Unfortunately, I don't know of any tool that could do this out of the box.
I am searching the web for a couple of days for any text generation model that would use only attention mechanisms.
The Transformer architecture that made waves in the context of Seq-to-Seq models is actually based solely on Attention mechanisms but is mainly designed and used for translation or chat bot tasks so it doesn't fit to the purpose, but the principle does.
My question is:
Does anyone knows or heard of a text generation model based solely on Attention without any recurrence?
Thanks a lot!
P.S. I'm familiar with PyTorch.
Building a character-level self-attentive model is a challenging task. Character-level models are usually based on RNNs. Whereas in a word/subword model, it is clear from the beginning what are the units carrying meaning (and therefore the units the attention mechanism can attend to), a character-level model needs to learn word meaning in the following layers. This makes it quite difficult for the model to learn.
Text generation models are nothing more than conditional languages model. Google AI recently published a paper on Transformer character language model, but it is the only work I know of.
Anyway, you should consider either using subwords units (as BPE, SentencePiece) or if you really need to go for character level, use RNNs instead.
Today I've been presented with a fun challenge and I want your input on how you would deal with this situation.
So the problem is the following (I've converted it to demo data as the real problem wouldn't make much sense without knowing the company dictionary by heart).
We have a decision table that has a minimum of 16 conditions. Because it is an impossible feat to manage all of them (2^16 possibilities) we've decided to only list the exceptions. Like this:
As an example I've only added 10 conditions but in reality there are (for now) 16. The basic idea is that we have one baseline (the default) which is valid for everyone and all the exceptions to this default.
Example:
You have a foreigner who is also a pirate.
If you go through all the exceptions one by one, and condition by condition you remove the exceptions that have at least one condition that fails. In the end you'll end up with the following two exceptions that are valid for our case. The match is on the IsPirate and the IsForeigner condition. But as you can see there are 2 results here, well 3 actually if you count the default.
Our solution
Now what we came up with on how to solve this is that in the GUI where you are adding these exceptions, there should run an algorithm which checks for such cases and force you to define the exception more specifically. This is only still a theory and hasn't been tested out but we think it could work this way.
My Question
I'm looking for alternative solutions that make the rules manageable and prevent the problem I've shown in the example.
Your problem seem to be resolution of conflicting rules. When multiple rules match your input, (your foreigner and pirate) and they end up recommending different things (your cangetjob and cangetevicted), you need a strategy for resolution of this conflict.
What you mentioned is one way of resolution -- which is to remove the conflict in the first place. However, this may not always be possible, and not always desirable because when a user adds a new rule that conflicts with a set of old rules (which he/she did not write), the user may not know how to revise it to remove the conflict.
Another possible resolution method is prioritization. Mark a priority on each rule (based on things like the user's own authority etc.), sort the matching rules according to priority, and apply in ascending sequence of priority. This usually works and is much simpler to manage (e.g. everybody knows that the top boss's rules are final!)
Prioritization may also be used to mark a certain rule as "global override". In your example, you may want to make "IsPirate" as an override rule -- which means that it overrides settings for normal people. In other words, once you're a pirate, you're treated differently. This make it very easy to design a system in which you have a bunch of normal business rules governing 90% of the cases, then a set of "exceptions" that are treated differently, automatically overriding certain things. In this case, you should also consider making "?" available in the output columns as well.
One other possible resolution method is to include attributes in each of your conditions. For example, certain conditions must have no "zeros" in order to pass (? doesn't matter). Some conditions must have at least one "one" in order to pass. In other words, mark each condition as either "AND", "OR", or "XOR". Some popular file-system security uses this model. For example, CanGetJob may be AND (you want to be stringent on rights-to-work). CanBeEvicted may be OR -- you may want to evict even a foreigner if he is also a pirate.
An enhancement on the AND/OR method is to provide a threshold that the total result must exceed before passing that condition. For example, putting CanGetJob at a threshold of 2 then it must get at least two 1's in order to return 1. This is sometimes useful on conditions that are not clearly black-and-white.
You can mix resolution methods: e.g. first prioritize, then use AND/OR to resolve rules with similar priorities.
The possibilities are limitless and really depends on what your actual needs are.
To me this problem reminds business rules engine where there is no known algorithm to define outputs from inputs (e.g. using boolean logic) but the user (typically some sort of administrator) has to define all or some the logic itself.
This might sound a bit of an overkill but OTOH this provides virtually limit-less extension capabilities: you don't have to code any new business logic, just define a new rule set.
As I understand your problem, you are looking for a nice way to visualise the editing for these rules. But this all depends on your programming language and the tool you select for this. Java, for example, has JBoss Drools. Quoting their page:
Drools Guvnor provides a (logically
centralized) repository to store you
business knowledge, and a web-based
environment that allows business users
to view and (within certain
constraints) possibly update the
business logic directly.
You could possibly use this generic tool or write your own.
Everything depends on what your actual rules will look like. Rules like 'IF has an even number of these properties THEN' would be painful to represent in this format, whereas rules like 'IF pirate and not geek THEN' are easy.
You can 'avoid the ambiguity' by stating that you'll always be taking the first actual match, in other words your rules have a priority. You'd then want to flag rules which have no effect because they are 'shadowed' by rules higher up. They're not hard to find, so it's something your program should do.
Your interface could also indicate groups of rules where rules within the group can be in any order without changing the outcomes. This will add clarity to what the rules are really saying.
If some of your outputs are relatively independent of the others, you will also get a more compact and much clearer table by allowing question marks in the output. In that design the scan for first matching rule is done once for each output. Consider for example if 'HasChildren' is the only factor relevant to 'Can Be Evicted'. With question marks in the outputs (= no effect) you could be halving the number of exception rules.
My background for this is circuit logic design, not business logic. What you're designing is similar to, but not the same as, a PLA. As long as your actual rules are close to sum of products then it can work well. If your rules aren't, for example the 'even number of these properties' rule, then the grid like presentation will break down in a combinatorial explosion of cases. Your best hope if your rules are arbitrary is to get a clearer more compact presentation with either equations or with diagrams like a circuit diagram. To be avoided, if you can.
If you are looking for a Decision Engine with a GUI, than you can try this one: http://gandalf.nebo15.com/
We just released it, it's open source and production ready.
You probably need some kind of inference engine. Think about doing it in prolog.
This question relates to project design. The project takes an electrical system and defines it function programatically. Now that I'm knee-deep in defining the system, I'm incorporating a significant amount of interaction which causes the system to configure itself appropriately. Example: the system opens and closes electrical contactors when certain events occur. Because this system is on an airplane, it relies on air/ground logic and thus incorporates two different behaviors depending on where it is.
I give all of this explanation to demonstrate the level of complexity that this application contains. As I have continued in my design, I have employed the use of if/else constructs as a means of extrapolating the proper configurations in this electrical system. However, the deeper I get into the coding, the more if/else constructs are required. I feel that I have reached a point where I am inefficiently programing this system.
For those who tackled projects like this before, I ask: Am I treading a well-known path (when it comes to defining EVERY possible scenario that could occur) and I should continue to persevere... or can I employ some other strategies to accomplish the task of defining a real-world system's behavior.
At this point, I have little to no experience using delegates, but I wonder if I could utilize some observers or other "cocoa-ey" goodness for checking scenarios in lieu of endless if/else blocks.
Since you are trying to model a real world system, I would suggest creating a concrete object oriented design that well defines the is-a and a has-a relationships and apply good old fashioned object oriented design and apply it into breaking the real world system into a functional decomposition.
I would suggest you look into defining protocols that handle the generic case, and using them on specific cases.
For example, you can have many types of events adhering to an ElectricalEvent protocol and depending on the type you can better decide how an ElectricalContactor discriminates on a GeneralElectricEvent versus a SpecializedElectricEvent using the isKindOfClass selector.
If you can define all the states in advance, you're best of implementing this as a finite state machine. This allows you to define the state-dependent logic clearly in one central place.
There are some implementations that you could look into:
SCM allows you to generate state machine code for Objective-C
OFC implements them as DFSM
Of course you can also roll your own customized implementation if that suits you better.
I am looking for tools to aid in the visualization of custom business logic used to perform document generation. The logic is expressed as an object-oriented model consisting of a graph of decision points and rendering actions. The basic building blocks are relatively simple, but the overall decision tree is quite large and complex making it hard to visualize.
We are looking for suggestions on tools and/or graphing libraries that can be used to visually represent the decision tree and rendering actions. The choice of programming language is not critical (Delphi, C#, Java would be great) and we are able to easily extract the logic to XML or other data format as required. The preference is for something that will run under Windows and enable printing or PDF output of portions of the resulting diagram.
Requirements
Decision points can be simple yes/no or multiple outputs e.g. (yes, not, sometimes, always etc).
The decision points are linked to external business logic that exist elsewhere in the runtime environment. We need to label the graph node with the type of decision point (e.g. boolean) and string describing the business rule being used.
Rendering actions are linked to named content objects with optional merge variables and inline rendering logic. At a minimum we need to be able to label nodes with the name of the element and ideally also information about variables used to render the content.
We have considered building something around Visio or WinGraphViz, or perhaps using a third-party graphing/flowchart library. Any ideas or pointers would be greatly appreciated.
After some more digging I found WinGraphViz and DotXML to be the closest match to my requirements. I was previously unaware of the "record" element which allows me to render decisions in the logic flow in a clean and legible manner.
You can consider Morphir with the Elm frontend.
It is a solid tool for business logic modeling, and code generation.
Visualization is coming along as well.