Wikipedia:Reference desk/Archives/Science/2013 May 5

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May 5

can one derive a language's grammar from sample code

Hello, this is out of idle curiosity, but can one derive a language's grammar from sample code? In other words, is it possible to write a program that, if fed code in some language wrote the EBNF that parsed the code , like this:
program xxx; var x: integer; begin x:=17; write(x); end. ===>
program::="program" ident; var-section main-block "."
var-section::="var" ident ":" type ";" etc, etc. (the names of the rules themselves need not be meaningful, obviously)
I suspect the program needs to have a way of knowing what the tokens are so it can tell between keywords and user-supplied identifiers. If the code sample was really big (it need not be a real program, either), such that it had every non-terminal in it and/or there were several snippets for when you can't put everything into one (one with no, one with a single and one with several variable declarations, for example), could one derive a complete grammar (or one of if there can be many) of the language? Thank you everyone in advance Asmrulz (talk) 01:42, 5 May 2013 (UTC)

Grammar induction is the article, though unsurprisingly the research focuses on natural languages. I don't know anything about this but I doubt you could find exactly the correct grammar of a programming language this way. Many programming languages don't have context-free (EBNF) grammars. For example the expression (A)(b) in C-like languages could be a type cast or a function call depending on how A was previously declared. -- BenRG 04:40, 5 May 2013 (UTC)

Hmmm...yes and no.

Strictly - no, it's not possible because you'd never know whether there might be some kind of construct that's not present in the example programs that you fed it. For example, you could pick an enormous corpus of C and C++ programs and never find a single one that uses the "goto" statement. I have written millions of lines of C/C++ code - and and read tens of millions more written by co-workers - and never once encountered a "goto". Even if you did find a few rare examples, it wouldn't be clear what the rules about jumping into and out of loops and subroutines are because you simply wouldn't have enough examples to deduce those things. I bet that it would be impossible to deduce the arcane rules for "goto" even if you took every C and C++ program ever written and analysed the whole lot.

But imperfectly - yes: Children can learn to understand and speak any language on the planet simply by listening to examples - and (in principle) anything that the human brain can do, you can do with a sufficiently powerful computer. However, children (and the adults they grow into) learn the language imperfectly...nearly everyone has some kind of failure of linguistics built into their brain.

SteveBaker (talk) 15:37, 5 May 2013 (UTC)

If the system only has source code, no it cannot extract the grammar. Children are able to learn laguage because they are exposed to two things: the language and its results. For instance Mother may say the word "custard" a few times while serving custard, so the child can associate the word custard with the actual stuff. Children also learn to speak because when they try it, their parents correct them. (Child: "wan custard"; Parent: "No, I want custard, please")

A computer program that deduces the grammar could in theory be constructed if it has access to both the source code, can run the source code, and can alter the source code. It motly cannot work out the complete grammar, for the reasons others have posted. Neither do humans ever completely master the vocabulary and grammar of spoken and written languages.

In practice, constructing a program that can deduce grammar of a computer language is probably not possible, because of the difficulty in understanding the meaning and scope of the output. I once wrote a program for an embedded processor in a hand held device. Each time you press the single "go" switch on it, after entering the 6-digit challenge number issued by the secure server you are trying to log into, it displays a 6-digit keycode that, with your own personal password, will enable you to log in. The keycode is generated by mashing the challenge (which was generated from a random number) and to the user appears to be another random number. No two challeges will ever be the same within a certain very low probability, and no two keycodes will ever be the same. Keying in the same challenge twice will give you two different keycodes. What is the proposed grammar extraction program to make of that?

Wickwack 120.145.68.194 (talk) 23:47, 5 May 2013 (UTC)

If you're correct about children needing parental feedback when they attempt to produce language from what they've learned about the grammar - then all that's needed to provide this for a grammar-learning program is access to a compiler for that language and a means to detect whether the resulting program compiled correctly. That's pretty much all a child gets.

But in this case, the computer has several advantages. Firstly, it's only being asked to learn the rules of the grammar - not to interpret what programs written in that grammar actually do. Your example of a tricky program is irrelevent...it's only tricky use of the grammar (like x=y++++z; or something) that's going to throw it. For example, it just needs to deduce that if a statement begins with the keyword "while", it is always followed by an expression surrounded by round brackets - followed by a statement. The program would have no idea that "while" is a looping construct or that the expression will not be executed once the expression evaluates to 'false'.

That's quite different from a parent pointing at a bowl of custard and saying "custard" to a child...the child is learning vocabulary in that case. I don't think parents ever explicitly teach things like "words that are verbs that end in "ed" are in the past tense".

Secondly: I also don't believe that children learn syntax by producing statements and being corrected. Our grandchild was quite able to understand "Fetch grandpa the duplo" long before she could speak a single word...and I'm fairly sure that children who do not have the ability to speak are perfectly able to learn enough grammar to understand what people say to them.

Thirdly, the program is only (presumably) being fed legal programs - where children hear all kinds of broken sentences, incorrect grammar and so forth.

SteveBaker (talk) 19:51, 6 May 2013 (UTC)

I agree, if the grammar extraction program has access to the compiler code, it can work out the grammar. It is an alternative to accessing the output. In fact, if you (or a machine) has the compiler source code, then you (or a machine) HAS the grammar to hand - all that may need to be done is to write it more concisely. I don't think that was what the OP had in mind though. He has talking about feeding the grammar extractor only examples of source code. Re your next point, undertsanding the vocabulary is essential to determining grammar - as BenRG pointed out. You have a point regarding the ability of children to understand spoken language with limited ability to speak themselves (and thus opportunities to hear corrections from others) - this has been an interesting field of study by certain linguists and psychologists. It appears that it is because children are born with a built in understanding of a "prototype" grammar, though it isn't English grammar. This is likely an advantage that a computer program cannot have, as there is an infinite range of possible computer proagram grammars. Finally, a grammar extraction machine that can deduce things like "statements can begin with while", as they do in some lenguages, or that "programs begin with program and end with end" as they do in Pascal, is not going to be generally useful. Many computer languages simply don't work that way - almost all assembly languages included. Ever tried to work out what someone else's assembly language does, having obtained a listing from ROM, which does not include any comments or pretty printing? That's a task fundamentally easier than deducing a grammar, never the less it isn't easy, dependent in practice on good guesses, exploring dead ends, and often very very difficult. Wickwack 60.230.238.42 (talk) 00:21, 7 May 2013 (UTC)

You're completely missing the point (again!) - the idea isn't to understand what a program DOES - the goal is to understand the grammar of the language that the program is written in. Sure, machine code programs can be hard to understand - but the grammar of the assembler is trivial: <label>:<opcode><argument>,<argument><comment> ...with a few of those parts being optional. I didn't say that the grammar extractor would have access to the source code of the compiler - just a means to generate a program and test whether it's legal or not...a boolean "good/bad" flag. But I don't think this is necessary. This is a difficult problem - but with enough variety of source code to examine, I think it's possible. However "enough variety of source code" might be a very tough barrier to making this work...as I explained with the difficulty of deducing the peculiar rules for the "goto" statement in C and C++ - given that almost nobody uses that horrible construct anymore. Just as children have "protogrammar" hard-wired, we could give our program knowledge such as "Most programming languages allow variables that start with a letter and are followed by any number of letters, digits and underscores" or "Most programming languages allow numbers that start with a +, - or a digit..." or "Some languages allow whitespace anywhere, others don't - figure out which of those is true before you start". There are all sorts of things that are common to so many languages - that you'd be able to figure them out. Of course there are deliberately obtuse languages (like Whitespace (programming language) that would defeat these rules...so this has limited value. SteveBaker (talk) 14:07, 7 May 2013 (UTC)

Sounds like you haven't worked with assembly code, Steve. The construct <label>:<opcode><argument>,<argument><comment> only exists at the time of writing. What gets stored in ROM (or whatever other form of memory is used) does not contain the labels or the comments. In any but the most trivial assembly routine, figuring out what are constants and what are opcodes can be a major effort in itself - they look the same, have the same range of values. Opcodes and constants both vary in byte length. And some smart-arse programmers not only use recursive techniques, some use self-modifying code. I can remember finally nutting out one bit of code where the author called the routine with two different entry points - one entry point restored and ran the routine pretty much as is, another entry point used a trick to use an opcode byte as a constant to change another opcode and completely change what the routine did!

I realise that the OP's question does not require the grammar extractor to understand what the program does, however it does need more than just source code of the target language. Yes, you didn't say that it needed access to the source code of the compiler - I misread that bit. However it did make me realise that being able to run and alter the source code is not the only way. However, your idea of just being able to run it thru the compiler to see if there are no compiler errors, or being able to run the program and see that there are no run time errors is not sufficient. If it was, there would have been no need for all the thousands of hours I've spent debugging code that did compile ok, and debugging code that ran ok too, until I or a colleague hit it with the right test case. And in some cases, after a couple of years use, the customer reported a bug! Even very strongly typed languages like Pascal can compile ok when the grammar has been violated. For example, passing a constant and then mistakenly treating it as a var (or a pointer) will compile ok, but the runtime result will usually be very different, and only sometimes trigger a runtime error. And as for that horrible nasty thing used for embedded control, the FORTH language, which is not typed at all and with which you can do anything one's smart arse lateral thinking heart desires..... That's why I misread what you said - I automatically assumed you didn't intend a simple go/no go run test because it is insufficient.

Wickwack 121.215.9.73 (talk) 14:59, 7 May 2013 (UTC)

Sodium hydroxide for washing dishes?

If I add sodium hydroxide to the water when washing up, I can convert triglycerides to the dark side and have the cleanest dishes ever? — Preceding unsigned comment added by 78.144.202.9 (talk) 02:07, 5 May 2013 (UTC)

Sure, go ahead, wash your dishes with drain opener, what do we care? Just make sure you wear gloves and googles and rinse very thoroughly. Looie496 (talk) 03:13, 5 May 2013 (UTC)

Internet search engines have the most surprising uses.  :) -- Jack of Oz ^[Talk] 03:18, 5 May 2013 (UTC)

Which triglycerides? Plasmic Physics (talk) 04:36, 5 May 2013 (UTC)

It doesn't matter, the lye will take care of any of them. --Jayron32 04:53, 5 May 2013 (UTC)

That depends on whether the lye is added in excess. Plasmic Physics (talk) 07:04, 5 May 2013 (UTC)

I'm just trying to figure out if the OP actually knows what they are talking about, because, by not defining 'triglycerides', there is no way to unambiguously interpret the question. Plasmic Physics (talk) 07:08, 5 May 2013 (UTC)

Triglycerides that make my dishes greasy? What are my options? 78.144.202.9 (talk) 07:15, 5 May 2013 (UTC)

Ordinary dishwashing liquid. NaOH is total overkill, and dangerous. -- Jack of Oz ^[Talk] 07:19, 5 May 2013 (UTC)

Doesn't that depend on how much I use? I could make it up to a less threatening concentration, or just add it to the water in its solid form... would it pop if I did that? — Preceding unsigned comment added by 78.144.202.9 (talk) 07:22, 5 May 2013 (UTC)

And when I said, what are my options, I meant re: the different types on triglycerides. — Preceding unsigned comment added by 78.144.202.9 (talk) 07:49, 5 May 2013 (UTC)

Sodium hydroxide is equally corrosive at all concentrations, except at 0 and 100 %. Varying the concentration only changes the reaction rate. Changing the amount, shifts the reaction equilibrium. Regardless, of concentration or amount of hydroxide used, it will still corrode glazes on cermics such as crockery, repeated use will strip the glaze off completely. While it does accomplish the task of degreasing, it also attacks the very thing you're trying to clean.

Note: it does not 'pop' when dissolved, that would be sodium metal igniting elemental hydrogen, given off by sodium metal. Plasmic Physics (talk) 08:26, 5 May 2013 (UTC)

Not to mention, how difficult it is to rinse off. If not rinsed completely, all food consumed from its surface will tase bitter and brackish, or similiar to baking soda, and it will damage your shelves. Plasmic Physics (talk) 03:38, 6 May 2013 (UTC)

It will also damage aluminium, zinc and tin. Rivets will tend to be eaten away. Graeme Bartlett (talk) 12:15, 5 May 2013 (UTC)

(Assuming those elemental forms and that type of object, are participant to this system.) Plasmic Physics (talk) 12:58, 5 May 2013 (UTC)

Adding to the list of others things you probably shouldn't wash your dishes in, you might enjoy this series from a professional chemist. Shadowjams (talk) 20:09, 5 May 2013 (UTC)

An alternative alkali to use is ammonia solution. It turns fats into soap, and cuts through high grease build up very fast. Try not to breathe the vapour. Graeme Bartlett (talk) 11:36, 9 May 2013 (UTC)

Pope alexander of the borgia family used vitriol or sulfur as a mood anhancer..

I cannot find anything anywhere on the internet about the ancient use of vitriol or sulfur as a mood enhancer nor how it was prepared and the side effects..can anyone please help me??

5/4/2013 10:28pm... — Preceding unsigned comment added by Jaime71355 (talk • contribs) 02:28, 5 May 2013 (UTC)

I'm afraid you might be mixed up -- I've never heard of anything like that and can't imagine how it would work. Is it possible that you're thinking of arsenic, which was sometimes used as a stimulant? Looie496 (talk) 03:18, 5 May 2013 (UTC)

I thought the Borgias only used arsenic against their enemies? 24.23.196.85 (talk) 06:06, 7 May 2013 (UTC)

Beef vs. chicken

Why is it alright to eat rare/medium beef but not chicken? Is salmonella not a problem with beef? DRosenbach ^{(Talk | Contribs)} 03:48, 5 May 2013 (UTC)

Because rare chicken tastes terrible. --Jayron32 04:04, 5 May 2013 (UTC)

Rare chicken is eaten in Japan, mostly in Kagoshima prefecture, in sashimi style like [1] and [2]. The taste is OK. But there's always a possiblity of Campylobacteriosis. I've eaten rare chicken twice, but nothing happened. Oda Mari (talk) 07:43, 5 May 2013 (UTC)

You can also get sick from undercooked beef. ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:24, 5 May 2013 (UTC)

Neither is "alright" - you can get sick from any type of food. It's really about statistics; and you've no doubt been exposed to more educational campaigns advising you about poultry - because that's where the majority of the reported infections come from. You are more likely to find hazardous bacteria in commercially-raised chicken than in commercially-raised beef. You can get sick from any harmful bacteria; and those bacteria can live almost anywhere - fruits, vegetables, meats, poultry, and non-food sources... but according to a report I found by browsing the USDA.gov website's food safety pages, An Economic Assessment of Food Safety Regulations: The New Approach to Meat and Poultry Inspection, salmonella accounts for more than half of all food-borne illness death, and accounts for about the same percentage of total health-care expense. E. coli infections, typically found in beef but also including all other sources, accounts for less than one tenth that amount. There is much speculation about why this is true: it is plausible that in the "natural environment," more chickens have illness, per capita, than cows. It is plausible that chickens are raised in conditions that are less sanitary or less healthy than cows. It is plausible that different regulations concerning beef and poultry contribute to a different epidemiology. It is plausible that testing for salmonella is less effective - or that hazardous quantities of poultry-borne salmonella are harder to detect than hazardous quantities of other food-borne pathogens. (In fact, the report I linked details each of these possibilities, with additional data). Nimur (talk) 18:27, 5 May 2013 (UTC)

And it's not just about eating rare vs. well-cooked meat. There's also the issue of defrosting frozen cooked meat. You can do that once, but if there's any left unused, you should get rid of it. If you refreeze it and defrost it a second time, it would no longer be safe to eat. This is particularly a risk for chicken, but it's true for all meat to some degree. -- Jack of Oz ^[Talk] 20:02, 5 May 2013 (UTC)

Different species harbor different organisms and the risk/transmission profile for them differs. There's not a lot of design beyond that. The one thing Nimur didn't mention is processing practices. Chickens are processed in bulk differently than cattle (the cleaning and defeathering for instance), and that can facilitate cross contamination. That said, even a single chicken from the backyard, dressed individually should probably be fully cooked. Shadowjams (talk) 20:07, 5 May 2013 (UTC)

• Great, but I think the OP is asking for illumination on “is it alright to eat rare/medium beef but not chicken.” This puts it so simply that even a child can understand: “Poultry roasts, however, have an added complication: Unlike solid beef roasts, chickens and turkeys have internal cavities that can be contaminated with bacteria. The central cavity will be the last part of a roast to cook, so to be safe, it's important to cook a whole chicken or turkey until a thermometer inserted into the thickest part of the thigh registers 165°F.” [3] So, in other words (and to answer the OP's question). It is not so much the bacteria but the nature of the meat that requires a cooking temperature to ensure that all pathogenics become 'toast.' Personally, I think raw meat is fine, providing that the chief buys it himself and knows what s/he is doing. But those artisans are far and few between. Having experienced food poisoning, I now trust only in people that have a solid local recommendation. Even if they comment : “ Uyee loook at mi daughter one more time like that … an' I'll smasher you face... OK? Bon appetite.”Aspro (talk) 17:12, 10 May 2013 (UTC)

Does frequent reading/writing affect neurology of spoken language?

The phenomena described in this article seem like they could be explained more or less like so: "Fans speak by reading their mental writing aloud; mundanes write by transcribing their mental speech." Have any studies examined how frequent reading and writing, and infrequent speaking, affect the brain structures or activation patterns associated with language? NeonMerlin 05:43, 5 May 2013 (UTC)

Athletes and alcohol

This is a hypothetical question, not medical advice, because I'm not a professional athlete. Before athletes compete, they follow a strict diet but say for example if they had a heavy night of drinking, a few days before, not a night before, how would that affect their performance on the day because I'm sure a few athletes must have tried this before whether, intentional or not. — Preceding unsigned comment added by Clover345 (talk • contribs) 12:06, 5 May 2013 (UTC)

None directly; the body has plenty of time to metabolize alcohol in a few days' time. The most likely avenue of affecting performance, in my opinion, is for the drinking and associated behavior to result in an arrest. Being in jail, or being suspended for having been in jail, is a sure means of preventing an athlete from performing normally. — Lomn 13:09, 5 May 2013 (UTC)

What about junk food? Do you think that would affect then more a few days before since they follow such a strict diet normally? Clover345 (talk) 14:33, 5 May 2013 (UTC)

It doesn't have a significant effect, the diet is relevant only for the long term. On the short run what counts is only if you are getting enough calories. Count Iblis (talk) 15:34, 5 May 2013 (UTC)

As this is a reference desk, here's one; The effects of Alcohol on Endurance Performance. It highlights these effects on the day after drinking:

• Dehydration
• Potassium and sodium depletion
• Impaired temperature regulation
• Impaired balance and co-ordination
• Reduced total work output

"... the ACSM recommends skipping anything beyond "low amount social drinking" for 48 hours prior to the event. It can take your body up to three days to purge itself of alcohol. One drink (sorry) over the course of an evening is your best bet." Alansplodge (talk) 16:46, 5 May 2013 (UTC)

You might find this article fascinating. Shadowjams (talk) 19:54, 5 May 2013 (UTC)

Optimizing learning habits

I've recently started playing games that are meant to improve the players' skill at solving simple arithmetic operations (such as 5×4 or 448÷32), which made me think about the way our brains study. For example, we will likely feel a bit uncomfortable whenever we make a mistake, which I suppose is the brain's way to make us more cautious. On the other hand, being too cautious would make us slower and therefore the learning process would take more time.

In order to accelerate my learning I wanted to know what consideration there are to the act of studying. What is the best time to study new information or to practice information that I've already learned? In the calculations games, should I prefer practicing each operation individually (first a list of additions, then subtraction and so forth) or all combined? Should I waste time to recalculate wrong results or should I move on? And how significant is it anyway?

In case the subject is too wide to detail, describing just the considerations of one habit (e.g. studying time) would also be great. I'm also interested in recommended books. Thanks! 79.181.175.168 (talk) 12:11, 5 May 2013 (UTC)

On whether to practice each operation individually or all combined, it really depends on what you want to achieve. If one particular operation is giving you problems, it would be a good idea to do that one individually. If you aren't having specific problems with any operation, it would be a good idea to do all combined, although I cannot quite remember the reason. Double sharp (talk) 15:11, 5 May 2013 (UTC)

Opinions differ widely on these sorts of things - from my own experience, there is no direct link from educational theory to educational practice to perfectly designed textbooks and educational systems. When you get to the act of "doing", there are just too many variables, and your own enjoyment of a system is one of them. But read up on Paul Pimsleur and spaced repetition. Basically, repeating immediately, then increasing the delay between each repetition, is the proven technique for memorising. This may or may not relate to solving mathematical puzzles, but I suggest it is a place to start. IBE (talk) 11:54, 6 May 2013 (UTC)

Is the blood test influenced by water?

I saw a nurse that say that if someone don't drink water before he come to a blood test, then his blood wouldn't come out as properly. My questions are: 1. Is it true? 2. Assuming this is true, How long it takes to the water to come into the blood circulation from the moment of the drinking. מוטיבציה (talk) 21:10, 5 May 2013 (UTC)

What 'blood test' would that be referring to. Richard Avery (talk) 21:40, 5 May 2013 (UTC)

Drinking a lot of water can dilute the blood - which I suppose would affect measurements of the amount of some substance per milliliter of blood...so yes, I assume it's true. Healthy kidneys are able to excrete 1 litre of water per hour...so the time it takes to return to normal will be at least one hour for every liter you drank. SteveBaker (talk) 22:23, 5 May 2013 (UTC)

It seems to me the question refers more to cases where people are (mildly) dehydrated and have low blood pressure as a result, causing problems with drawing blood... Count Iblis (talk) 23:08, 5 May 2013 (UTC)

As the OP supposes, it is not a question of affecting lab measurements, it is a question of how easy or difficult it is for the nurse to get blood out of the patient. Mild dehydration in basically healthy patients does not affect difficulty in drawing blood. In elderly patients, and in patients who have been given intravenous chemotherapy, the peripheral veins that are normally chosen to draw blood, which are the same ones they tend to choose for intravenous drips, tend to harden and partially close down. In such patients, drawing blood can be quite difficult, but if they drink plenty of water 20 to 60 minutes before, it can be easier. In my experience, (as an elderly patient who has had chemo) it seems to depend on the experience and skill of the nurse. Older nurses, and nurses that have specialised in taking blood (phlebotomists) don't seem to have a problem regardless, as they will choose a better vein, and they are better at getting the canula in. Time of day also matters. If a doctor orders a blood test that requires fasting (for which the normal way is to get the blood taken before breakfast), on a cold morning nurses cannot get blood out of my arm veins at all - blood has to be taken from a foot vein, which requires a doctor's direct supervision for some reason. Wickwack 120.145.68.194 (talk) 23:27, 5 May 2013 (UTC)

Just a slight correction, the term is phlebotomist, it has nothing to do with plebs or botany :) Vespine (talk) 02:28, 6 May 2013 (UTC)

Last summer my GP practice had a notice up to the effect that patients who have booked morning blood tests should drink a pint of water after they get up and before they come for their blood test, so the phlebotomist there obviously think it affects the process. --TammyMoet (talk) 10:33, 6 May 2013 (UTC)

Interesting. I have about 6 blood tests a year these days, and the issue has never been raised. When it's a fasting test, they always ask when was the last time I ate; but otherwise, no questions. -- Jack of Oz ^[Talk] 10:41, 6 May 2013 (UTC)

You have to book an appointment to get blood taken, Tammy?? Another reason why I'm glad I don't live in the UK and have to put up with the NHS. We in Australia (not noted for a good caring medical system either) just rock up when we get round to it. I've never had to wait more than 5 minutes. Wickwack 121.221.85.77 (talk) 14:19, 6 May 2013 (UTC)

We do have a choice: I can go and sit in the out-patients at my local hospital and queue to have my blood taken without an appointment, or I can make an appointment to see the phlebotomist at my GP's surgery, or at one of several pharmacies around town, or I can arrange for a private phlebotomist to come to my house for a fee of £15 and take my blood. The advantage of the GP option is they have free parking. The disadvantage is that, when I faint (which I do from time to time) while having the blood taken, they have to call an ambulance and get my husband out of work and I go to A&E. If I'm at the hospital, I get charged parking fees of £2 per hour. If I faint they wheel me round to the recovery area and make an internal call to my husband, who works in IT there. Guess which I prefer. --TammyMoet (talk) 19:00, 6 May 2013 (UTC)

We have these choices: 1) go to the phlebotomist at a GP's premises (all are private) - if you faint, they'll just get the doctor to sort you out - calling an ambulance to take you away from a doctor on hand and to to A & E where you'll have to get past the triage is just plain silly. No parking fee, due to competitive pressure; 2) Go to a laboratory's blood taking outlet - all private - there are heaps of them all over the place, typically in shopping centres - no parking fee. What would happen if you faint is unknown to me, I guess they would have to call an ambulance, but maybe not - all phlebotomists are fully trained State Registered Nurses. 3) Go to the phlebotomist at a private hospital - no parking fee usually; 4) Go to the phlebotomist at a public (ie Goverment owned) hospital - pay an outrageous parking fee and wait. Public hospital phlebotomists are the most skilled though. If you genuinely can't leave home, a nurse from the Silver Chain will come, take blood, admister treatments etc. Silver Chain are a Not-or-Profit organsiation and there is no fee regardless of what service is provided. However, if you can think rationally and talk, they will ask for a donation and can be quite aggressive about it. For those with terminal cancer and want to spend their last months or days in their own bed at home, away from hospital noise and hospital food, Silver Chain are absolutely marvelous. Overall, yep, I'm glad I don't live in the UK and have to put up with the NHS. Wickwack 60.230.238.42 (talk) 00:47, 7 May 2013 (UTC)