In previous decades, the journalistic mission was to report the news as it actually happened, with fairness, balance, and integrity. However, capitalistic motives associated with journalism have forced much of today s television news to look to the spectacular, the stirring, and the controversial as news stories. It s no longer a race to break the story first or get the facts right. Instead, it s to acquire good ratings in order to get advertisers, so that profits soar. News programming uses a hierarchy of if it bleeds, it leads. Fear-based news programming has two aims. The first is to grab the viewer s attention. In the news media, this is called the teaser. The second aim is to persuade the viewer that the solution for reducing the identified fear will be in the news story. If a teaser asks, What s in your tap water that YOU need to know about? a viewer will likely tune in to get the up-to-date information to ensure safety.

It s the end of CentOS as we know it Earlier this week, the CentOS project announced the shift to CentOS stream. In a nutshell, this means that they will discontinue being a close clone of RHEL along with security updates, and instead it will serve as a development branch of RHEL. As you can probably imagine (or gleam from the comments in that post I referenced), a lot of people are unhappy about this. One particular quote got my attention this morning while catching up on this week s edition of Linux Weekly News, under the distributions quotes section:

I have been doing this for 17 years and CentOS is basically my life s work. This was (for me personally) a heart wrenching decision. However, i see no other decision as a possibility. If there was, it would have been made.Johnny Hughes

Throw me a freakin bone here I m also somewhat skeptical of how successful CentOS Stream will really be in any form of a community project. It seems that Red Hat is expecting that volunteers should contribute to their product development for free, and then when these contributors actually want to use that resulting product, they re expected to pay a corporate subscription fee to do so. This seems like a very lop-sided relationship to me, and I m not sure it will be sustainable in the long term. In Red Hat s announcement of CentOS Stream, they kind of throw the community a bone by saying In the first half of 2021, we plan to introduce low- or no-cost programs for a variety of use cases - it seems likely that this will just be for experimental purposes similar to the Windows Insider program and won t be of much use for production users at all. Red Hat does point out that their Universal Base Image (UBI) is free to use and that users could just use that on any system in a container, but this doesn t add much comfort to the individuals and organisations who have contributed huge amounts of time and effort to CentOS over the years who rely on a stable, general-purpose Linux system that can be installed on bare metal.

Way forward for CentOS users Where to from here? I suppose CentOS users could start coughing up for RHEL subscriptions. For many CentOS use cases that won t make much sense. They could move to another distribution, or fork/restart CentOS. The latter is already happening. One of the original founders of the CentOS project, Gregory Kurtzer, is now working on Rocky Linux, which aims to be a new free system built from the RHEL sources. Some people from Red Hat and Canonical are often a bit surprised or skeptical when I point out to them that binary licenses are also important. This whole saga is yet another data point, but it proves that yet again. If Red Hat had from the beginning released RHEL with free sources and unobfuscated patches, then none of this would ve been necessary in the first place. And while I wish Rocky Linux all the success it aims to achieve, I do not think that working for free on a system that ultimately supports Red Hat s selfish eco-system is really productive or helpful. The fact is, Debian is already a free enterprise-scale system already used by huge organisations like Google and many others, which has stable releases, LTS support and ELTS offerings from external organisations if someone really needs it. And while RHEL clones have come and gone through the years, Debian s mission and contract to its users is something that stays consistent and I believe Debian and its ideals will be around for as long as people need Unixy operating systems to run anywhere (i.e. a very long time). While we sometimes fall short of some of our technical goals in Debian, and while we don t always agree on everything, we do tend to make great long-term progress, and usually in the right direction. We ve proved that our method of building a system together is sustainable, that we can do so reliably and timely and that we can collectively support it. From there on it can only get even better when we join forces and work together, because when either individuals or organisations contribute to Debian, they can use the end result for both private or commercial purposes without having to pay any fee or be encumbered by legal gotchas. Don t get caught by greedy corporate motivations that will result in you losing years of your life s work for absolutely no good reason. Make your time and effort count and either contribute to Debian or give your employees time to do so on company time. Many already do and reap the rewards of this, and don t look back. While Debian is a very container and virtualization friendly system, we ve managed to remain a good general-purpose operating system that manages to span use cases so vast that I d have to use a blog post longer than this one just to cover them. And while learning a whole new set of package build chain, package manager and new organisational culture and so on can be uhm, really rocky at the start, I d say that it s a good investment with Debian and unlikely to be time that you ll ever felt was wasted. As Debian project leader, I m personally available to help answer any questions that someone might have if they are interested in coming over to Debian. Feel free to mail leader_AT_debian.org (replace _AT_ with @) or find me on the oftc IRC network with the nick highvoltage. I believe that together, we can make Debian the de facto free enterprise system, and that it would be to the benefit of all its corporate users, instead of tilting all the benefit to just one or two corporations who certainly don t have your best interests in mind.

Issues with Farm Laws While I have written about the farm laws a bit sometime back. The issue is still in the nation s eye and that is due to the policies which have been done. I have been reading up on it quite a bit and also have been seeing what has been happening in here and now. The problems are with the three bills themselves which I have shared as below Click to access farmers-produce-trade-and-commerce-promotion-and-facilation-bill.pdf Click to access farmers-empowerment-and-protection-bill.pdf Click to access essential-commodities-bill-2020.pdf Biggest issue with the laws While there are many issues with the laws themselves but for me the biggest issue is that the fundamental right of the farmer to get justice via civil courts has been railroaded. From the laws itself. Standard disclaimer not a lawyer, please consult one for any issues per-se.

Farmers-produce-trade-and-commerce (promotion and facilitation-bill) 2020 Page 4 Chapter 3 Section 8 (1)8. (1) In case of any dispute arising out of a transaction between the farmer and a trader under section 4, the parties may seek a mutually acceptable solution through conciliation by filing an application to the Sub-Divisional Magistrate who shall refer such dispute to a Conciliation Board to be appointed by him for facilitating the binding settlement of the dispute. (2) Every Board of Conciliation appointed by the Sub-Divisional Magistrate under sub-section (1), shall consist of a chairperson and such members not less than two and not more than four, as the Sub-Divisional Magistrate may deem fit.10 (5) If the parties to the transaction under sub-section (1) are unable to resolve the dispute within thirty days in the manner set out under this section, they may approach the Sub-Divisional Magistrate concerned who shall be the Sub-Divisional Authority for settlement of such dispute. (8) Any party aggrieved by the order of the Sub-Divisional Authority may prefer an appeal before the Appellate Authority (Collector or Additional Collector nominated by the Collector) within thirty days of such order who shall dispose of the appeal within thirty days from the date of filing of such appeal. 10. (1) Any person aggrieved by an order under section 9 may, prefer an appeal within sixty days from the date of such order, to an officer not below the rank of Joint Secretary to the Government of India to be nominated by the Central Government for this purpose: Page 6 of the bill. 13. No suit, prosecution or other legal proceedings shall lie against the Central Government or the State Government, or any officer of the Central Government or the State Government or any other person in respect of anything which is in good faith done or intended to be done under this Act or of any rules or orders made thereunder. Page 7 of the bill, 15. No civil court shall have jurisdiction to entertain any suit or proceedings in respect of any matter, the cognizance of which can be taken and disposed of by any authority empowered by or under this Act or the rules made thereunder. Now the same laws have been reiterated for the farmers (Empowerment and Protection) Agreement on Price Assurance and Farm Services Bill, 2020. The problem is that too much power is being put into the hands of the executive. All the three, whether it is SDM (Sub-Divisional Magistrate) , the Appellate Authority or the Government Secretary directly are subservient to the whims and fancies of the Central Govt. They after all get their salaries from the Govt. itself. So there will be no independent oversight to any injustices done to the farmer. The third bill i.e. the Essential Commodities Bill, 2020 does away with stock limits on traders and big players like Adani and Ambani. This means that both these players can take and keep produce at their end thereby forcing consumers like you and me who at the retail end would have to pay higher prices for fruits and vegetables while from the producer they will take at the lowest price possible. While I have shared is just one of the points. That is the reason why even the Supreme Court bar association which almost never takes part in politics has been forced to take sides with the farmers. In many ways, one is forced to remember the Emergency Update 11/12/20 Came across this article on the wire which tells how everybody s rights, not just the farmer s rights are being shod over. I think it depicts correctly the signs of time to come. While arguing on SM, also came to know about Article 300 (1), thanks to Sachin Kumar which shows multiple instances where Government was sued because somebody was working in official capacity and did mistakes, malafide or otherwise and it was the state who was made to pay. FWIW, today farmers from Maharashtra, my state arrived at Delhi border where they were also kept at bay. I did come across an infographic which shows how the various states have fared. Most tellingly, is the state of Bihar. It was in 2006 (one of the most backward states) where APMC was taken off. While others have tried to paint a flattering picture of Bihar, they have failed to share that in the interim 15 odd years, there hasn t been any sort of infrastructure created for farmers which is the reason it is still the lowest earner. These are the last available figures we have about the farmer s income. From 2014 to 2020 there hasn t been any update.

Situation Assessment Survey of Agricultural Household 2013 Copyright GOI,

This concludes just one portion of the bill. I will take other parts of the bill. I may dwell on some other parts as and when I have the time. A cartoon which depicts the current issue

I stand with farmers Copyright Sanitary Panels

Too much democracy Amitabh Kant Yesterday, the Niti Aayog chief Amitabh Kant remarked that we are too much of a democracy at an event called for Atmanirbhar Bharat which is basically a coinage for import substitution. Whether this is desirable or not I have argued and if needed will re-argue the same later as well. What is and was interesting were the gentleman s context, the media reactions and our overall Democracy Index which has been going downhill for quite some years. Now the gentleman who is the Niti Aayog chief and who is supposed to have the ear of the Prime Minister had opined it in an event organized by Swarajya Magazine (a far-right magazine) known to be Islamophobic and all things undemocratic. It has been a target of defundthehate campaign and with good reason. But that s a different story altogether. His full statement was as below

Tough reforms are very difficult in the Indian context, as we are too much of a democracy but the government has shown courage and determination in pushing such reforms across sectors, including mining, coal, labour and agriculture. Niti Aayog chief. The upper quotation remarks and the statement has been from the article in Indian Express which I have linked to. I have archived it as a pdf just in case the link goes dead. Yesterday, after the statement became viraled, tweets of media houses which shared the tweet suddenly become unavailable. Seems too much democracy, became too little democracy all of a sudden. I think Mr. Amitabh Kant didn t visualize as the opposition as well as most people who are on Twitter to share their opinion on the same. Few examples

Too much Democracy copyright Satish Acharya

Too much democracy Illustration and Copyright Alok

Sterlite protest 13 dead, 100 injured Copyright Business Standard too much democracy

Erosion of Democracy V-dem institute Copyright The Hindu Web Team

The last one requires a bit more information. This comes from V-Dem Institute which is an independent research institute based out of Department of Political Science, University of Gothenburg, Sweden. I am gonna leave the methods they use for another day as the blog post itself has become rather big/large. Apart from that is the Economists own Democracy Index -2019 Click to access democracy-index-2019.pdf Now for many people, both the V-Dem report and the Economist Index are some sort of attack against India. Doesn t matter that in V-Dem 200+ countries have been taken a variety of indicators and data or the Economist which has data from 150+- countries. Somehow India is supposed to be bigger than all these countries, they do think that other countries data specifically our neighbor China or any other neighbor, those are all accurate. How the dissonance is, has to be gauged from statements of various people. Update 11/12/20 Sadly, the newest V-Dem report marks India as getting into authoritarianism. Gag on Press and Media owners I had shared about the gag on the press especially with respect to western media or reports or anything. This news made its way to straitstimes which normally covers a wide-range of stories covering East Asia vis-a-vis India/South-East Asia. What has also been a big worry that most of the media has been in the hands of a few people. Caravan ran a story on the same in 2016, it has been four years, god only knows what the current situation might be. Any wonder that there is dearth of investigative journalism in India.

India media ownership 2016 Copyright Caravan

Incidentally, a reporter called Akarshan Uppal, who is a reporter on a channel called IBN24 had showecased just few days back how Adani has got land which was shot down for land change use in 2017 to 2020 around 100 acres. There seem to be very less details as to how the land was acquired, whose land it was etc. etc. The reporter was supposedly following a story on drugs on which he was attacked and is now lying in hospital.

Akarshan Uppal Reporter, IBN24 Copyright IBN24

While it would take a whole article/blog post to talk about either Adani or Ambani, in the recent case, the land that has been taken over by Adani is 100 acres and there are private rail lines. And all of this was secret till few days back. The place where these massive godowns/silos have been made are Panipat s Jondhan Kalan and Naultha villages in Haryana. This is Adani AgiLogistics. Almost 7 odd companies have registered and come up in the last couple of years. As can be seen, almost all have come up within the last 2-3 years. Seems to be a lot of coincidence, isn t it?

Personal Anecdote on Data Collection and child marriages in India.

Around 1995 -96 when Internet had started to become a thing in India, there had been quite a few non-profits which were working on various issues. One of those which I initially came in contact with and which I found to be a bit absurd was non-profit which was working in the field of women against Violence. Now it is and was not the concept or the idea which was absurd to me, it was what these women were doing. Instead of the traditional ways in which you counsel women and try and figure out issues, these women were collecting data points from newspapers and magazines. This was way way before data science became a thing in India. They had their own structure where a story about violence against women which would be above the fold would be 5 points, the one below 2.5 points, in inner pages, it would be less and less. Patriarchy at that time was so strong, even today is but at that time it was such, that it felt a waste of time. I did consult them but never said that but did privately feel the above. In hindsight, they were doing the right thing and yet even today crimes against women goes unreported and is suppressed by both State and Central Governments as well as NCRB (National Crime Records Bureau). Interestingly, just few days back, the case against M.J. Akbar by Priya Ramani had taken a back seat and the defamation case by M.J. Akbar was taken forward. Even then, Priya Ramani s counsel s arguments were such that the court wound up in half an hour when they were expecting to do a whole day hearing. The next hearing would be happening today which I will look at in few hours from now. Why Priya Ramani was singled out rather than other tweets may probably be because she is an NRI and most NRI s usually do not want to be part of the bureaucratic Indian court system. This is also the reason that most companies from outside India especially those who are into startups prefer to change ownership, IPR etc. to their own or any country outside India which does make a loss to the exchequer. But this again is a story for another day. At the end, while I did not want to end on a negative note, it seems in many ways status-quo remains. For e.g. 2 years back, a BJP candidate (part of the ruling dispensation) had made a controversy saying that if they win the police won t interfere in child marriages. This is and was in Rajasthan where they have been trying to eradicate it forever. Till date, neither the NHRC (National Human Rights Commission) nor NCW (National Commission for Women) has taken cognizance of the statement. This is our state of democracy.

contact=ads@fmarier.org

• https://feeding.cloud.geek.nz/ads.txt
• https://fmarier.org/ads.txt

Specification The key parts of the specification for our purposes are:

[3.1] If the server response indicates the resource does not exist (HTTP Status Code 404), the advertising system can assume no declarations exist and that no advertising system is unauthorized to buy and sell ads on the website. [3.2.1] Some publishers may choose to not authorize any advertising system by publishing an empty ads.txt file, indicating that no advertising system is authorized to buy and sell ads on the website. So that consuming systems properly read and interpret the empty file (differentiating between web servers returning error pages for the /ads.txt URL), at least one properly formatted line must be included which adheres to the format specification described above.

As you can see, the specification sadly ignores RFC8615 and requires that the ads.txt file be present directly in the root of your web server, like the venerable robots.txt file, but unlike the newer security.txt standard. If you don't want to provide an email address in your ads.txt file, the specification recommends using the following line verbatim:

placeholder.example.com, placeholder, DIRECT, placeholder

Validation A number of online validators exist, but I used the following to double-check my setup:

• https://adstxt.guru/validator/url/?url=https%3A%2F%2Ffeeding.cloud.geek.nz%2Fads.txt
• https://www.adstxtgenerator.com/validator/results/?site=feeding.cloud.geek.nz

• [1] https://tinyurl.com/y4mnsech
• [2] https://tinyurl.com/yxctvs7t
• [3] https://tinyurl.com/glvopyp
• [4] https://inequality.org/
• [5] https://tinyurl.com/y3a8o87s
• [6] https://tinyurl.com/yxcxoc6z
• [7] http://egypt.urnash.com/rita/chapter/01/
• [8] https://tinyurl.com/yyr3fquz
• [9] https://www.youtube.com/watch?v=0jk2i3HTMpw
• [10] https://threadreaderapp.com/thread/1327253991936454663.html
• [11] https://tinyurl.com/y22gfbaw
• [12] https://tinyurl.com/y4rg4wps

• the Debian server Linux guest created with the "Linux Center" app can be accessed using SSH with the admin/admin login/pwd (couldn't find a clue in the docs or the UI)
• the "Mount shared folder" option in the Debian guest configuration leads to the "/.share/" mountpoint which exibits the NAS filesystem under the Linux guest. This allows to retrieve files being backedup to the NAS to be copied out with rsync
• backupninja provides an rsync handler which allows to backup files with rsync, but some default options weren't valid (see debian bug #976650).
• the Seagate ironwolf HD less that 4TB aren't compatible with IHM (Ironwolf Health Management), even if the "Storage Manager" app tends to mislead you.

• [DLA 2446-1] moin security update for two CVEs
• [DLA 2451-1] libvncserver security update for one CVE
• [DLA 2459-1] golang-1.7 security update for two CVEs
• [DLA 2460-1] golang-1.8 security update for three CVEs
• [DLA 2468-1] tcpflow security update for one CVE
• [DLA 2469-1] qemu security update for five CVEs

• ELA-319-1 for libass
• ELA-320-1 for tcpflow
• ELA-321-1 for qemu

• golang-github-apparentlymart-go-cidr
• golang-github-apparentlymart-go-versions
• golang-github-bmatcuk-doublestar
• golang-github-cactus-go-statsd-client
• golang-github-cyberdelia-heroku-go
• golang-github-gin-contrib-cors
• golang-github-gin-contrib-gzip
• golang-github-jarcoal-httpmock
• golang-github-mattetti-filebuffer
• golang-github-nrdcg-goinwx
• golang-github-phpdave11-gofpdi
• golang-github-terra-farm-udnssdk
• meep
• golang-github-rs-zerolog

• libctl

• bottlerocket
• ent
• golang-github-abdullin-seq
• golang-github-bruth-assert
• golang-github-cnf-structhash
• golang-github-crossdock-crossdock-go
• golang-github-dchest-uniuri
• golang-github-deanthompson-ginpprof
• golang-github-dreamitgetit-statuscake
• golang-github-facebookgo-inject
• golang-github-facebookgo-structtag
• golang-github-gin-contrib-static
• golang-github-goji-httpauth
• golang-github-grafana-grafana-plugin-model
• golang-github-hansrodtang-randomcolor
• golang-github-hashicorp-terraform-svchost
• golang-github-icrowley-fake
• golang-github-jackc-fake
• golang-github-joyent-gocommon
• golang-github-joyent-gosdc
• golang-github-joyent-gosign
• golang-github-mitchellh-go-linereader
• golang-github-paypal-gatt
• golang-github-pearkes-cloudflare
• golang-github-pearkes-dnsimple
• golang-github-robfig-go-cache
• golang-github-sean pager
• golang-github-sean seed
• golang-github-shurcool-gopherjslib
• golang-github-vividcortex-mysqlerr
• golang-github-xlab-handysort
• golang-github-yudai-golcs
• golang-github-yvasiyarov-newrelic-platform-go
• golang-github-zenazn-goji
• golang-github-rs-xid

• golang-github-rhnvrm-simples3
• golang-github-ua-parser-uap-go
• golang-github-knadh-koanf

The need for case names Consider the following Coq proof, right out of the respected Software Foundations book, Chapter Inductively Defined Propositions (and slightly simplified):

Lemma star_app: forall T (s1 s2 : list T) (re : reg_exp T),
  s1 =~ Star re ->
  s2 =~ Star re ->
  s1 ++ s2 =~ Star re.
Proof.
  intros T s1 s2 re H1.
  remember (Star re) as re'.
   generalize dependent s2.
  induction H1.
  - (* MEmpty *) discriminate.
  - (* MChar *) discriminate.
  - (* MApp *) discriminate.
  - (* MUnionL *) discriminate.
  - (* MUnionR *) discriminate.
  - (* MStar0 *)
    injection Heqre' as Heqre''. intros s H. apply H.
  - (* MStarApp *)
    injection Heqre' as Heqre''.
    intros s3 H1. rewrite <- app_assoc.
    apply MStarApp.
    + apply H1_.
    + apply IHexp_match2.
      * rewrite Heqre''. reflexivity.
      * apply H1.
Qed.

This is a very typical example for a proof by induction over an inductively defined relation (in this case, the relations s =~ re which indicates that the string s matches the regular expression re): After some preparation, the invocation of a tactic like induction (could also be inversion or others) creates a number of new goals, one of for each rule of the relation. Then the modern(!) Coq user uses proof bullets to focus the goals, one after another, in order, to solve them. We can see from this example that proof bullets (which were a big improvement) are not quite satisfactory, and the author of this proof felt the need to annotate each subproof with the case it corresponds to. But these are mere comments! This is unsatisfactory, as there is nothing keeping them correct as my proof changes. And anyone who came to Coq from Isabelle is just flabbergasted that the state of art in Coq is still at that level So, wouldn t it be great if

• I could focus goals by their name (e.g. MEmpty)
• Focus them in any order (so that refactoring of my data types do not break my proofs)
• This even worked when simultaneously inducting over or inverting multiple relations?

Simulating named goals in Coq Well, with a few tricks we can! It just takes three simple steps:

1. I load a small file full of hacks (explained below):

   Require Import NamedCases.

2. This allows me to prefix the type of the constructors of the inductive relations (i.e. the rules of the relation) with case <name>, , as follows:

   Reserved Notation "s =~ re" (at level 80).
   Inductive exp_match  T  : list T -> reg_exp T -> Prop :=
       MEmpty:
       case empty,
       [] =~ EmptyStr
       MChar:
       case char,
       forall x,
       [x] =~ (Char x)
       MApp:
       case app,
       forall s1 re1 s2 re2
       (H1 : s1 =~ re1)
       (H2 : s2 =~ re2),
       (s1 ++ s2) =~ (App re1 re2)
       MUnionL:
       case union_l,
       forall s1 re1 re2
       (H1 : s1 =~ re1),
       s1 =~ (Union re1 re2)
       MUnionR:
       case union_r,
       forall re1 s2 re2
       (H2 : s2 =~ re2),
       s2 =~ (Union re1 re2)
       MStar0:
       case star0,
       forall re,
       [] =~ (Star re)
       MStarApp:
       case star_app,
       forall s1 s2 re
       (H1 : s1 =~ re)
       (H2 : s2 =~ (Star re)),
       (s1 ++ s2) =~ (Star re)
     where "s =~ re" := (exp_match s re).

   This is the definition from the Software Foundations book; only the case <name>, lines are added.
3. Now I can change the proof: After the induction tactic I use ; name_cases to name the cases, and then I can use the relatively new named goal focusing feature ([name]: , which I suggested two years ago, and was implemented by Th o Zimmermann) to focus a specific case:

   Lemma star_app2: forall T (s1 s2 : list T) (re : reg_exp T),
     s1 =~ Star re ->
     s2 =~ Star re ->
     s1 ++ s2 =~ Star re.
   Proof.
     intros T s1 s2 re H1.
     remember (Star re) as re'.
      generalize dependent s2.
     induction H1; name_cases.
     [empty]:  
        discriminate.
      
     [char]:  
        discriminate.
      
     [app]:  
        discriminate.
      
     [unionL]:  
        discriminate.
      
     [unionR]:  
       discriminate.
      
     [star0]:  
       injection Heqre' as Heqre''. intros s H. apply H.
      
     [starApp]:  
       injection Heqre' as Heqre''.
       intros s3 H1. rewrite <- app_assoc.
       apply MStarApp; clear_names.
       + apply H1_.
       + apply IHexp_match2.
         * rewrite Heqre''. reflexivity.
         * apply H1.
       
   Qed.

   The comments have turned into actual names!

Goal focusing is now just much more reliable. For example, let me try to discharge the boring cases by using ; try discriminate after the induction. This means there are suddenly only two goals left. With bullets, the first bullet would now suddenly focus a different goal, and my proof script would likely fail somewhere. With named goals, I get a helpful error message No such goal: empty and I can t even enter the first subproof. So let me delete these goals and, just to show off, focus the remaining goals in the wrong order:

Lemma star_app: forall T (s1 s2 : list T) (re : reg_exp T),
  s1 =~ Star re ->
  s2 =~ Star re ->
  s1 ++ s2 =~ Star re.
Proof.
  intros T s1 s2 re H1.
  remember (Star re) as re'.
   generalize dependent s2.
  induction H1; name_cases; try discriminate.
  [starApp]:  
    injection Heqre' as Heqre''.
    intros s3 H1. rewrite <- app_assoc.
    apply MStarApp; clear_names.
    + apply H1_.
    + apply IHexp_match2.
      * rewrite Heqre''. reflexivity.
      * apply H1.
    
  [star0]:  
    injection Heqre' as Heqre''. intros s H. apply H.
   
Qed.

I did not explain the clear_names tactic yet that I had to use after apply MStarApp. What I am showing here is a hack, and it shows these case names are extra hypothesis (of a trivially true type CaseName), and this tactic gets rid of it.

Even better than Isabelle The above even works when there are multiple inductions/inversions involved. To give an example, let s introduce another inductive predicate, and begin proving a lemma that one can do by induction on one and inversion on the other predicate.

Inductive Palindrome  T  : list T -> Prop :=
  EmptyPalin:
  case emptyP,
  Palindrome []
  SingletonPalin:
  case singletonP,
  forall x,
  Palindrome [x]
  GrowPalin:
  case growP,
  forall l x,
  Palindrome l -> Palindrome ([x] ++ l ++ [x])
.
Lemma palindrome_star_of_two:
  forall T (s : list T) x y,
  Palindrome s -> s =~ Star (App (Char x) (Char y)) ->
  s = [] \/ x = y.
Proof.
  intros T s x y HPalin HRe.
  induction HPalin; inversion HRe; name_cases.

At this point we have four open goals. Can you tell why there are four, and which ones they are? Luckily, Show Existentials will tell us their names (and Coq 8.13 will just show them in the proof state window). These names not only help us focus the goal in a reliable way; they even assist us in understanding what goal we have to deal with. For example, the last goal arose from the GrowP rule and the StarApp rule. Neat!

  [emptyP_star0]:  
    left. reflexivity.
   
  [emptyP_starApp]:  
     left. reflexivity.
   
  [singletonP_starApp]:  
    inversion HRe; clear HRe.
    inversion H5; clear H5.
    inversion H10; clear H10.
    inversion H11; clear H11.
    subst.
    inversion H3.
   
 [growP_starApp]:  
    admit. (* I did not complete the proof *)
  

Under the hood (the hack) The above actually works, but it works with a hack, and I wish that Coq s induction tactic would just do the right thing here. I hope eventually this will be the case, and this section will just be curiosity but until, it may actually be helpful.

1. The trick¹ is to leave markers in the proof state. We use a dedicate type CaseName, and a hypothesis name : CaseName indicates that this goal arose from the that case.

   Inductive CaseName := CaseNameI.

   With this, we can write StarApp: forall (starApp : CaseName), to name this case.
2. For a little bit of polish, we can introduce notation for that:

   Notation "'case' x , t" := (forall  x : CaseName , t) (at level 200).

   This allows us to use the syntax you saw above.
3. To easily discharge these CaseName assumptions when using the introduction forms, I wrote these tactics:

   Ltac clear_names := try exact CaseNameI.
   Ltac named_constructor  := constructor; [ exact CaseNameI   idtac .. ].
   Ltac named_econstructor := econstructor; [ exact CaseNameI   idtac .. ].

4. Finally I wrote the tactic name_cases. What it does is relatively simple:

   For each subgoal: Take all hypotheses of type CaseName, concatenate their names, change the name of the current goal to that, and clear these hypotheses

   Unfortunately, my grasp of Coq tactic programming is rather rudimentary, and the only way I manged to solve this is a horrible monster of Ltac2, including hand-rolled imperative implementations of string concatenation and a little nested Ltac1 tactic within. You have been warned:

   From Ltac2 Require Import Ltac2.
   From Ltac2 Require Option.
   Set Default Proof Mode "Classic".
   Ltac name_cases := ltac2:(
     (* Horribly manual string manipulations. Does this mean I should
        go to the Ocaml level?
     *)
     let strcpy s1 s2 o :=
       let rec go := fun n =>
         match Int.lt n (String.length s2) with
           true => String.set s1 (Int.add o n) (String.get s2 n); go (Int.add n 1)
           false => ()
         end
       in go 0
     in
     let concat := fun s1 s2 =>
       let l := Int.add (Int.add (String.length s1) (String.length s2)) 1 in
       let s := String.make l (Char.of_int 95) in
       strcpy s s1 0;
       strcpy s s2 (Int.add (String.length s1) 1);
       s
     in
     Control.enter (let rec go () :=
       lazy_match! goal with
         [ h1 : CaseName, h2 : CaseName  - _ ] =>
         (* Multiple case names? Combine them (and recurse) *)
         let h := concat (Ident.to_string h1) (Ident.to_string h2) in
         Std.clear [h1; h2];
         let h := Option.get (Ident.of_string h) in
         assert ($h := CaseNameI);
         go ()
         [ _ : CaseName  - _ ] =>
         (* A single case name? Set current goal name accordingly. *)
         ltac1:(
           (* How to do this in ltac2? *)
           lazymatch goal with
             [ H : CaseName  - _ ] => refine ?[H]; clear H
           end
         )
         [  - _ ] =>
         Control.backtrack_tactic_failure "Did not find any CaseName hypotheses"
       end
     in go)
   ).

   If someone feels like re-implementing this in a way that is more presentable, I ll be happy to update this code (and learn something along the way

That s all it takes!

Conclusion With some mild hackery, we can get named cases in Coq, which I find indispensable in managing larger, evolving proofs. I wonder why this style is not more common, and available out of the box, but maybe it is just not known well enough? Maybe this blog post can help a bit here.

---

1. I have vague recollections of seeing at least parts of this trick on some blog some years ago, and I do not claim originality here.

export MESA_EXTENSION_OVERRIDE="-GL_EXT_bgra -GL_EXT_texture_format_BGRA8888"

$ warzone2100 
/usr/bin/gdb: warning: Couldn't determine a path for the index cache directory.
27      ../sysdeps/unix/sysv/linux/wait4.c: No such file or directory.
No frame at level 0x7ffc3392ab50.
Saved dump file to '/home/etbe/.local/share/warzone2100-3.3.0//logs/warzone2100.gdmp-VuGo2s'
If you create a bugreport regarding this crash, please include this file.
Segmentation fault (core dumped)

• [1] https://tinyurl.com/y5y3cpgq

• start from ubuntu:21.04 to be able to install g++-11 later
• install the software-properties-common package to be able to add a PPA
• (plus a few more packages to deal with the repository signing key)
• run the sudo add-apt-repository ppa:ubuntu-toolchain-r/volatile command to add the volatile packages PPA
• install g++-11 (along with, for good measure) gcc-11 and gfortran-11
• use update-alternative (a clever Debian/Ubuntu command) to make version 11 the default
• install R itself (via r-base-core) which we simply take from the distro as 21.04 is by construction very recent
• install Rcpp via the r-cran-rcpp binary which covers all dependencies for the package in question

edd@rob:~/git/rcpptoml(master)$ docker run --rm -ti -v $PWD:/mnt -w /mnt rocker/r-edge:gcc-11 g++ --version
g++ (Ubuntu 11-20201128-0ubuntu2) 11.0.0 20201128 (experimental) [master revision fb6b29c85c4:a331ca6194a:e87559d202d90e614315203f38f9aa2f5881d36e]
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

edd@rob:~/git/rcpptoml(master)$ 
edd@rob:~/git/rcpptoml(master)$ docker run --rm -ti -v $PWD:/mnt -w /mnt rocker/r-edge:gcc-11 R CMD INSTALL RcppTOML_0.1.7.tar.gz
* installing to library  /usr/local/lib/R/site-library 
* installing *source* package  RcppTOML  ...
** using staged installation
** libs
g++ -std=gnu++11 -I"/usr/share/R/include" -DNDEBUG -I../inst/include/ -DCPPTOML_USE_MAP -I'/usr/lib/R/site-library/Rcpp/include'    -fpic  -g -O2 -fdebug-prefix-map=/build/r-base-Fuvi9C/r-base-4.0.3=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -g  -c RcppExports.cpp -o RcppExports.o
g++ -std=gnu++11 -I"/usr/share/R/include" -DNDEBUG -I../inst/include/ -DCPPTOML_USE_MAP -I'/usr/lib/R/site-library/Rcpp/include'    -fpic  -g -O2 -fdebug-prefix-map=/build/r-base-Fuvi9C/r-base-4.0.3=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -g  -c parse.cpp -o parse.o
g++ -std=gnu++11 -shared -L/usr/lib/R/lib -Wl,-Bsymbolic-functions -Wl,-z,relro -o RcppTOML.so RcppExports.o parse.o -L/usr/lib/R/lib -lR
installing to /usr/local/lib/R/site-library/00LOCK-RcppTOML/00new/RcppTOML/libs
** R
** inst
** byte-compile and prepare package for lazy loading
** help
*** installing help indices
** building package indices
** testing if installed package can be loaded from temporary location
** checking absolute paths in shared objects and dynamic libraries
** testing if installed package can be loaded from final location
** testing if installed package keeps a record of temporary installation path
* DONE (RcppTOML)
edd@rob:~/git/rcpptoml(master)$ 

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

• grow faster, wasting more disk space and duplicating data.
• increase the amount of necessary I/O during cluster allocation,
  reducing the allocation performance.

• Sixteen times less metadata per unit of allocation, greatly reducing the amount of necessary L2 cache.
• Much faster I/O during allocating when the image has a backing file, up to 10-15 times more I/O operations per second for the same cluster size in my tests (see chart below).
• Smaller images and less duplication of data.

• The performance improvements described earlier happen during allocation. Writing to already allocated (sub)clusters won t be any faster.
• If the image does not have a backing file chances are that the allocation performance is equally fast, with or without extended L2 entries. This depends on the filesystem, so it should be tested before enabling this feature (but note that the other benefits mentioned above still apply).
• Images with extended L2 entries are sparse, that is, they have holes and because of that their apparent size will be larger than the actual disk usage.
• It is not recommended to enable this feature in compressed images, as compressed clusters cannot take advantage of any of the benefits.
• Images with extended L2 entries cannot be read with older versions of QEMU.

$ qemu-img create -f qcow2 -o extended_l2=on,cluster_size=128k img.qcow2 1T