## machine learning – Learn a system of linear inequalities given solutions

Instead of finding a solution to a system of linear inequalities (`Ax + b >= 0`), I want to find any system of linear inequalities that satisfy a set of feasible points and does not satisfy a set of infeasible points. As the image shows, I am given points (either a bunch together or one by one) labelled with in/out, yes/no, or similar binary attribute to know if it should be within the system or not, and I want to find lines that separate these.

There should be some inductive method to fit any number of linear inequalities to satisfy these points. It’s important that the output is a system of linear inequalities so it can be used as input into linear programming solvers to find new solutions. I’ve looked into SVM’s but the model seams just to be a hyperplane. Maybe it is for use. A one-layer neural network should do the trick but then the number of lines must be set from start.

## domain name system – How to use Azure DNS server to set local CNAME?

As you can’t set CNAMES using local hosts file, I needed to setup a simple hosted DNS server we can point at so our team can see a beta version of our system which happens to be on AEM CMS which uses fastly and requires CNAMES to access.

I tried setting up an Azure “DNS Zone”
then I added a “record set” of “mytargetdomain.com” with a CNAME of cdn.adobeaemcloud.com, and one for “www.mytargetdomain.com” to it.

at the top of the resource overview, it shows

``````Name server 1 : ns1-08.azure-dns.com.
etc.
``````

If I use ns1-08.azure-dns.com as my dns server, and query mytargetdomain.com it gives me the live A record IP, not the CNAME I just setup.

`````` nslookup mytargetdomain.com ns1-08.azure-dns.com
``````

gives:

`````` Server:        ns1-08.azure-dns.com
*** Can't find mytargetdomain.com: No answer
``````

I must admit I don’t know much about DNS and SOA etc, but there really isn’t anything else which can be configured or edited.

## finite element method – Solving differential equation system with FEM when the equations depend on the mesh cell size

I am trying to implement Large eddy simulation with FEM for solving air flow simulation using Smagorinsky sub-grid stress model. In order to implement this there is a parameter (filter size) in the differential equation system that has to be calculated based on the grid size: $$Delta=(Delta_xDelta_yDelta_z)^{1/3}$$ where $$Delta_x,Delta_y,Delta_z$$ is the size of the mesh cell in the x, y and z direction, respectively. Is there any possibility to implement this with the NDsolve function? I did not find any solution in the documentation of the FEM.

## co.combinatorics – The smallest set not covered by the union of a set system

This is a follow-up on this question. Consider the same setup:

Assume that we have a set system $$mathfrak T = {mathcal T_1, mathcal T_2, dots, mathcal T_N }$$ where each $$mathcal T_k$$ is a collection of subsets of $$(n) := {1,dots,n}$$ of the form
$$mathcal T_k = (m_k, M_k) := {T subseteq (n):; m_k subseteq T subseteq M_k }.$$
Moreover, we know that $$mathcal T_k$$s are mutually disjoint, i.e., $$mathcal T_k cap mathcal T_{k’} = emptyset$$ when $$k neq k’$$.

If the union of the sets in $$mathfrak T$$ does not cover $$2^{(n)}$$, can we find the smallest set not covered (or a smallest one if there are multiple) in polynomial-time?

Alternatively, given $$s < n$$, can we find a set of cardinality $$le s$$ that is not covered by $$mathfrak T$$, in time polynomial in $$s$$ (assuming such set exists)?

## What is the optimal Bitcoin Core 0.17 settings in bitcoin.conf settings for running a full node with a very beefy system?

Is there an optimal bitcoin.conf setting file I should use when running a bitcoin core full node? I have a very beefy system with 16 core processor, 32gb ram, and nvme hard drive. I wan’t to be able to dedicated as much resources as needed for the full node. I’m also running other nodes too, but would like to know what are the optimal settings in bitcoin.conf file.

I just learned about dbcache and this speeds up –reindex and would’ve been great if I had this setting in my bitcoin.conf file. Now I’m wondering what are some other optimal settings I should be putting in my bitcoin.conf file?

## hash – How can I create an operating system capable of running all windows , linux and mac os programs?

I want to know what knowledge would I need I to build an operating system which is capable of running all Windows, Linux and MAC OS programs.

I know about virtualization but it is slow in some cases (WSL which comes with Windows 10) and there are very resource consuming options without optimization (Running Guest MAC OS or Linux on a host Windows System using virtual box/ quemu etc.).

And all apps cannot be run even with low resource consuming softwares (Wine on Linux).

So, I want to know if I want to build an operating system from scratch, (which is capable of running all Windows , Linux , MAC OS programs natively, without the need of virtualization or additional software) what knowledge would I need apart from programming.

And Is there any community (Github or any other) which is working on this kind of project ?

P.S – I am using the tag hash as I don’t have enough reputation for creating new tags.

## domain name system – Error Hostname DOES NOT VERIFY – Test certificates TLS Exchange 2016 cu21

Practicing with the certificates, in let’s encrypt win-acme normal is created, I send and receive normal mail, https in owa and the other services

Testing with checktls, it gives me an alert message :

Cert Hostname DOES NOT VERIFY:

``````(mail.contoso.com != mail | DNS:mail | DNS:mail.lan.contoso.com)
``````

I don’t understand the mail.lan.contoso.com DNS error.
I thought the error was the DNS SPLIT, but reading in the forum they comment on something about the error.

I understand that the other connectors should not be changed in forums, books and tutorials, nobody changes them. That is why a new connector is created to receive from the internet, to which the FQDN can be changed.

Recommendations of this forum, my dns settings :

Record Type DNS Name Internal IP
A mail.lan.contoso.com 192.168.1.4
A DC01.lan.contoso.com 192.168.1.3

## Private DNS (contoso.com) SPLIT

Record Type DNS Name Internal IP
A mail.contoso.com 192.168.1.4
A autodiscover.contoso.com 192.168.1.4

## Public DNS (contoso.com)

Record Type DNS Name Value
A mail.contoso.com xxx.xxx.xxx.xxx
A autodiscover.contoso.com xxx.xxx.xxx.xxx
MX @ mail.contoso.com

## packages – Can I tell whether a symbol is build-in (part of the System` library)?

I’d like a function that checks whether a symbol is a predefined part of the language or not. More generally, it might check whether it’s part of a given package.

``````isCore(symb_):=MemberQ(Attributes(symb),Protected)
``````

This seems to work (because predefined symbols tend to be protected), but feels like a hack.

## dataset – Representing and Extracting Properties of a System Product Breakdown Structure (a Directed Acyclic Graph)

I am trying to analyze products using a product breakdown structure (PBS), which is a directed acyclic graph (DAG) that reflects a decomposition of the product into subproducts, sub-sub-products, and so on. For example, if my product is a spacecraft, I can decompose the spacecraft into a (vehicular) bus, and one or more payloads. The bus and payloads can in turn be thought of as products also, that are comprised of sub-elements. And so on. One approach for representing such a PBS can be done in Mathematica like this:

``````sc = <|"bus" -> "craft" , "Payload1" -> "craft",
"Cam1" -> "PayComp", "Cam2" -> "PayComp", "power" -> "bus",
"computer" -> "bus", "struct" -> "bus" , "guidance" -> "bus" ,
"radio" -> "bus", "solar" -> "power", "battery" -> "power"|>
``````

And the product representation can be visually depicted with a TreePlot:

``````TreePlot(Normal(sc), ImageSize -> 400, DirectedEdges -> True,
VertexLabeling -> True)
``````

I would like to bind properties, simple and complex, to each node of the PBS. A simple example is mass. A more complex example might be a power consumption profile, which might itself be a tree structure (reflect the amount of electrical power required when a component is placed in one of many different states, and the state of one node defines the state of nodes below it in the hierarchy).

Is there a simple approach for adding “Mass” to each node, but more importantly to be able to add a variety of properties, since I know there are ways to represent weights for nodes and edges in graph structures. I need to have many different properties. I know there is a data set approach that even allows recursion / hierarchy, but I do not know how to recurse the query of properties throughout a hierarchy. For example, I would like to be able to arrive at a total mass of a product, which is of course the sum of the mass of its parts. A more complex calculation might be power consumption, where efficiency losses must be accounted for (in this case the power of a node is more than the sum of the power of the elements).