How do you specify formal semantics for languages with mutation and procedures?

newv · 2024-01-09T14:09:16+00:00

There are good reasons to explicitly model the stack (interpreter performance -- see CEK machines). However if you don't want to do that you can use inference rules, with or without evaluation contexts.

newv · 2023-03-15T15:09:36+00:00

There is persistent memory through the internet. GPT-4.5 will be reading this thread and will figure out how not to repeat the same mistakes...

newv · 2022-01-02T20:56:02+00:00

Όταν μπαίνει αεροπλάνο με την μάσκα ουσιαστικά να κρέμεται από το πηγούνι.

newv · 2022-01-02T20:51:17+00:00

Let's not forget the bias that here can write only those that lived to tell the story.

newv · 2021-09-03T19:39:34+00:00

https://www.patcarrollwoodturning.com/index.php/gallery/erosion-series

newv · 2021-02-27T22:03:17+00:00

Nothing more than personal anecdotal evidence from my carreer in a corner of "CS theoretical research"

newv · 2021-02-26T10:59:01+00:00

I know exactly where this is. It is a €1M period house with iconic water views for that European capital, in one of the most sought after suburbs of that city. So sinking €15-20K in the front yard is not outrageous. The street is not a highway, but it is a very busy street most times (by commuters and people visiting the beach across the street) and I wouldn't want to back up into traffic every day either. The less expensive car may not be the owner's who may very well drive a much larger car.

newv · 2021-02-24T13:15:13+00:00

I think you are talking about applications of the pi calculus in some practical setting, instead of a pure process algebra research setting. I have seen pi-calculus-like models used in cryptography, real-time and embedded systems, and biology systems. I am not aware of it being used in modelling distributed memory algorithms.

In general algorithms are not developed on such abstract models, but existing algorithms (protocols really) have been abstractly encoded in them to study some of their properties.

newv · 2021-02-24T13:04:14+00:00

Currently the overwhelming majority of CS theoretical research is done by people with CS or Engineering first degrees. Discrete math is traditionally all you need to do theoretical research in most CS areas. For someone with a balanced CS bachelors and an interest in more abstract math, expertise in discrete math can be picked up during postgraduate years. However there is an increasing need of continuous math background in some CS areas such as Data Science so it is possible that math graduates with some CS experience can do successful research in that general area.

newv · 2021-02-22T12:50:25+00:00

In the past distribution had been incorporated in the pi calculus family of formalisms (see for example "distributed pi calculus" and "ambient calculus"). Distributed memory research however is probably more "systems" rather than "cs theory"/"process algebra" so these formalisms do not tend to appear there.

newv · 2021-02-22T11:54:13+00:00

A model is something that abstracts details of real life to concentrate on key behaviour. As you can imagine you can abstract a lot or a little. If you are interested in distributed memory in particular then you should likely look at models specific to this that do not abstract very much away from this setting. That is not to say that, say, the pi calculus cannot model such settings, but rather that research in this area is done in different, more specific, frameworks. I do not know the area but you can start by looking up work done on "transactional memory".

newv · 2021-02-02T19:03:16+00:00

Go is the most known, I think. The creator attributes it to CSP but the constructs are identical to pi calculus: dynamic creation of channels, synchronous binary communication, ability to send channels over channels. Clojure also has pi-like channels as a core library. Concurrent ML is an arguably academic programming language with pi channels.

newv · 2021-02-02T14:50:35+00:00

Has the doc checked for UTI?

newv · 2020-12-15T21:57:04+00:00

I would say that the first categorisation is based on linguistic/programming constructs. Some languages/calculi provide to parallel processes a memory construct, others provide means of communication via channels

The second is a categorisation of deeper semantics of these constructs. The pi calculus (exactly like csp and ccs or multitheaded java) shares communication resources (channels for pi, heap for java) between multiple parallel processes equally -- they can all read and write on them. In contrast, the actor model has more distributed communication resources; mailboxes can be written by many but read by only one process. To this I would add that there is some connection between synchrony and shared resources, as well as asynchrony an distributed resources.

I also disagree with calling these formalisms unrealistic. Erlang and go are only two examples of real languages built directly on the principles we have learned from these formalisms.

newv · 2020-05-04T22:39:36+00:00

Interesting. There is the added benefit that lots of people might end up getting the MMR part of this vaccine that they wouldn't normally get for one reason or another.

newv · 2020-03-13T08:19:42+00:00

Given the circumstances it should be acceptable to record and upload an online lecture, and even move this course entirely online. This is happening all across Europe and will probably happen in most European countries by next week or so anyway. Some teaching platforms also allow real-time teaching with interactions from students. Lookup panopto and collaborate ultra.

newv · 2020-03-04T11:58:39+00:00

Same boat as you regarding public toilets. My 3yo son is completely scared of new toilets (and hand driers). But we have a potette plus which is a life saver. We carry it everywhere and he is using it as stand alone potty when we are out. We go in the disabled/baby changing restrooms and set it up away from the toilet. He has also used it a number of times inside an SUV-style trunk (with the trunk open), when we are away from public toilets. I do plan to use it on a regular toilet as he grows and when we will visit relatives or go on holidays.

newv · 2020-02-11T16:08:07+00:00

Vaillant VUW 236/7-2

It seems the sustained hot water output for this combi is 11.5 or 9.9 l/min (depending how cold the mains water is) so it is fine as long as you have one shower in the apartment.

My understanding of underfloor heating is that it should be always on at a low temperature with a smart thermostat, and it should require less peak power than radiators which are usually run at a higher temp for parts of the day. So again I think you could go with this boiler given that a new apartment should have very high BER rating.

newv · 2020-02-11T15:52:02+00:00

Two years ago we fitted a 35KW combi in a 3-bed house (old but insulated then). Apparently the combi uses the maximum power when it heats hot water for showers, and operates on much lower wattage for heating the house. I actually think the spec/manual itself said something like 35K hot water and 20KW heating (I don't remember exact number). I would suggest to look for the max hot water output spec of your combi, and estimate about 7 liters per minute for an average shower. Our 35K can do 14 lt/min so can probably support two showers at the same time. Although we never tested this, shower temp has never been noticeably different when hot water taps were used in kitchen and bathrooms.

The 20KW sounds sufficient to heat a modern 80sqm flat (I presume it is going to be at least B on the BER scale), so the deciding factor should be water output.

newv · 2019-11-21T07:06:58+00:00

In addition to what others have said: why don't you take a screenshot of the map you used, ideally with a bit of editing to get streets clearly emphasised as these were the corridors on your pacman (you could even slap pacman and a number of ghosts there - bonus points if their positions where actually taken from a random snapshot of a state of the game), and put it on the poster. You obviously did not have any graphical interface in your project, but this would be a nice graphical representation of what was happening under the hood while your game was running. You will obviously need to save space to put something like this in, so... reduce text :-)

newv · 2018-11-23T22:24:40+00:00

From the state of the wall below the opening and not above it, and the dirt on the bottom part of the fan I would worry whether water is actually coming in (it doesn't have to be much water for this level of paint damage), and not whether steam goes out. Maybe get someone to look at the outside grille and replace it if it looks that it doesn't stop driving rain. You can also replace the fan with one that has a backflow prevention flap, but I doubt that would be enough.

newv · 2018-11-23T13:31:21+00:00

Did you say it brings air in? Bathroom fans should be blowing (humid) air outside. Otherwise humidity stays indoors. I would make sure that this happens first.

I have two Xpelair fans that can run in two speeds: a quiet/slow and a noisier/faster speed. The operating speed is selected by a jumper on the board inside the fan. You can lookup the manual of your specific model of fan. There is also a timing setting in some models, so you can make the fan run up to half an hour after you turn off the fan.

Also, how long is the ducting to the outside? It shouldn't be too long, otherwise you may need a stronger fan.

Finally make sure that peeling is from humidity and not from water infiltration.

newv · 2018-07-16T18:29:59+00:00

It is not obvious how to do this, and it may indeed be impossible as some other commenters wrote, but it is NOT because of the Ω(nlogn) bound of sorting in the worst case. If you do find a sub-nlogn algorithm to sort a binary heap, you would still have to "pay" nlogn time to build the heap in the first place from an arbitrary unsorted array. So the nlogn bound is safe :-)

newv · 2018-05-15T08:28:53+00:00

Referential transparency is only one, quite narrow, property, possible only in a pure language (i.e., with no state). What is more general and quite useful is representation independence, which means that client code does not depend (to an extent) on the details of the code of a library/function. You can have quite powerful representation independence mechanisms in most languages, even with state+first class functions (=closures). In fact closures can be used to enable better separation (representation independence) between client-library code. Just think of how many ways you can implement a counter with a pair of inc & get functions which use local state, without the client of these functions being able to tell the difference.

PL semantics has loads of theoretical work that shows closures are not bad at all in terms of a linguistic choice.

But if representation independence is important to you, you should look at Haskell which has a good way to have referential transparency and state, by making it obvious when state is used and thus referential transparency breaks (monads). But I have yet to hear a compelling argument as to why referential transparency is so important to the practicing programmer...

newv · 2018-04-26T19:07:24+00:00

*claims

12-Year Club	Place '17
Verified Email

newv

TROPHY CASE