Artur Meski

Mon, 01 Jan 0001 00:00:00 +0000

Hello,

I’m Dr Artur Meski, a software engineer and researcher with a PhD in formal methods.

You can find a list of my academic publications on Google Scholar and DBLP.

I am also passionate about photography. You can view some of my photos on my photography website.

ReactICS

Mon, 01 Jan 0001 00:00:00 +0000

Formal verification of reaction systems

Reaction systems are a formalism inspired by the functioning of living cells. They allow for specification and analysis of computational processes in which reactions operate on sets of entities (or molecules).

The behaviour of a reaction system is determined by the interactions of its reactions, which are based on the mechanisms of facilitation and inhibition. The formal treatment of reaction systems is qualitative and there is no direct representation of the number of entities involved in reactions.

Contact

Mon, 01 Jan 0001 00:00:00 +0000

You can send me encrypted email using OpenPGP.

Email: artur@meski.io

Fingerprint: FFAA FE4B AC80 6BDE EC5F 38EB AE6B 6A76 7CD5 E1B4

Public key: Download ASCII-armored public key

DHCP Lease Monitor

Mon, 01 Jan 0001 00:00:00 +0000

This is a daemon for monitoring lease changes on OpenBSD for the specified interfaces. When a change happens it then calls a script located in /etc/dhcpleasemon. The script name should be:

lease_trigger_<interface>

The script has access to the following environment variables:

$DHCP_IFACE – interface name
$DHCP_IP_ROUTE – default route for the interface
$DHCP_IP_ADDR – IP address from the lease

The daemon is implemented in Rust and is available on GitHub.

PhD Thesis

Mon, 01 Jan 0001 00:00:00 +0000

Here you can find my PhD thesis and the slides I used during my public PhD defence.

Abstract

Reaction systems are a formal model inspired by the functioning of living cells. This model allows for specifying and analysing computational processes in which reactions operate on sets of molecules.

The behaviour of a reaction system is determined by the interactions of its reactions, which are based on the mechanisms of facilitation and inhibition. The formal treatment of reaction systems is qualitative and there is no direct representation of the number of molecules involved in reactions.

Model checking for distributed reaction systems with temporal-epistemic properties

Wed, 05 Nov 2025 00:00:00 +0000

Authors

Artur Meski
Maciej Koutny
Łukasz Mikulski
Ion Petre
Wojciech Penczek
Marcin Piatkowski

Abstract

Reaction systems are a model of computation inspired by the biochemistry exhibited by living cells. This paper introduces the notion of agency as an extension to the reaction systems formalism, leading to distributed reaction systems. Adding agents in the reaction systems setting, allows for the natural modelling and representation of multi-agent and distributed systems. To support the specification of temporal-epistemic properties of distributed reaction systems, we introduce the logic rsCTLK and present experimental results of its associated model checking procedure run on a biological benchmark of within-cell signal transduction networks. The experimental results are encouraging despite the complexity of the rsCTLK model checking problem that is shown to be PSPACE-complete.

Limiting resources on FreeBSD

Fri, 09 Sep 2022 00:00:00 +0000

What is `rctl`

In FreeBSD, in addition to login.conf, we also get a very nice and flexible mechanism for setting resource limits: rctl. I like it in particular for limiting resources allocated to each jail.

Configuration

Here is a short example:

jail:example_jail:vmemoryuse:deny=2G/jail
jail:example_jail:maxproc:deny=200/jail
jail:example_jail:readiops:throttle=500/jail
jail:example_jail:pcpu:deny=70/jail

In the above, for the jail identified by example_jail we allow:

2G of memory,
200 processes,
500 I/O read operations per second,
70% of CPU.

Enabling rctl on boot

Actually, there is no need to enable anything in rc.conf – this is what you can find in /etc/defaults/rc.conf:

Public VMs on OpenBSD

Wed, 28 Jul 2021 00:00:00 +0000

This is a note on how to make a VM running on OpenBSD connect to the host’s network.

Firstly, we need to create a bridge with our external network interface.

# echo "em0" > /etc/hostname.bridge0
# /etc/netstart bridge0

In /etc/vm.conf we need to add a switch on bridge0:

switch "sw" {
    interface bridge0
}

Then, our VM needs to be attached to that switch:

vm "openbsd" {
    memory 8G
    enable
    disk /data/vm/openbsd/main.qcow2
    interface tap {
	switch "sw"
    }
}

My network setup also requires to specify the MAC address of the network interface:

Basic concurrency with fork()

Wed, 23 Jun 2021 00:00:00 +0000

When programming on Linux/Unix, the function fork(2) allows us to create new processes. This is a short and example-driven introduction to the basics of using that function.

First stab

After a brief look at the manual page for fork(2) we can tell that it returns a value of type pid_t and does not take any arguments:

NAME
     fork – create a new process

SYNOPSIS
     #include <unistd.h>

     pid_t
     fork(void);

Let us simply call fork and see what happens and what values does it return.

Quick start: virtual machines on OpenBSD

Sat, 19 Jun 2021 00:00:00 +0000

Since OpenBSD 5.9 it is possible to run virtual machines using a native virtualisation solution.

This is a short note/guide on how to set up a VM on OpenBSD in the simplest way that lets you have a quick play with vmm/vmd.

Preliminaries

First of all, we need to enable vmd on our host and get it running:
```
# rcctl enable vmd
# rcctl start vmd
```
You may also want to make sure you firewall can initially let everything through:

Reading and monitoring files on Linux

Sat, 19 Jun 2021 00:00:00 +0000

Let’s start with something super basic. To print the contents of a file you can use cat:

cat file

This tool is simple but really powerful when combined (piped) with other commands. However, cat is not very practical if you just want to see the contents of a larger file. In that case you can use less, which also allows you to conveniently browse your file:

press space for page down or b for page up,
type /pattern to search for pattern in the file (n jumps to the next occurence, while N jumps to the previous one),
press q to quit.

If you need to watch a certain file (typically a log file), you can simply use tail -f:

Model checking temporal properties of reaction systems

Thu, 20 Aug 2015 00:00:00 +0000

Authors

Artur Meski
Wojciech Penczek
Grzegorz Rozenberg

Abstract

This paper defines a temporal logic for reaction systems (rsCTL). The logic is interpreted over the models for the context restricted reaction systems that generalise standard reaction systems by controlling context sequences. Moreover, a translation from the context restricted reaction systems into boolean functions is defined in order to be used for a symbolic model checking for rsCTL over these systems. The model checking for rsCTL is proved to be PSPACE-complete. The proposed approach to model checking was implemented and experimentally evaluated using four benchmarks.

Artur Meski

ReactICS

Formal verification of reaction systems

Contact

DHCP Lease Monitor

PhD Thesis

Abstract

Model checking for distributed reaction systems with temporal-epistemic properties

Authors

Abstract

Limiting resources on FreeBSD

What is rctl

Configuration

Enabling rctl on boot

Public VMs on OpenBSD

Basic concurrency with fork()

First stab

Quick start: virtual machines on OpenBSD

Preliminaries

Reading and monitoring files on Linux

Model checking temporal properties of reaction systems

Authors

Abstract

What is `rctl`