Regex NFA construction: Why use Glushkov over Thompson? Pros/Cons

In what circumstances should we prefer Glushkov’s algorithm or Thompson’s construction for the building of regular expression NFAs?

I understand the difference between them, and can follow the argument for each approach.

I understand that the result is an NFA in each case, but with a lack of $ \epsilon$ -transitions in Glushkov’s approach, and that this presumably results in a minor[?] match-time implementation-complexity benefit and a reduction in the total number of states for a given expression?

Are these the primary criteria to recommend Glushkov?

It appears that the Glushkov construction process may be more complex than Thompson. Is this the case? Does this argue for Thompson for projects where that is a factor?

Are there other important factors affecting the implementation choice which I am unaware of?

System Nav Bar Required? If not, pros/cons for keeping it?

Haven’t worked on an Android app in a bit and was wondering if the system navigation bar needs to be there or not.

Nav Bar

Looking at my husbands phone (I am on iOS), it’s not on any of his apps. Is there a new best practice in this regard? I was looking in Google’s Material Design guidelines and it doesn’t say it’s a mandate. Moreover, the Android Developers Guide shows ways to hide it.

I posted this on some Slack channels I am on and some designers are saying it’s required while others are saying it’s not, so I’d love tor get your thoughts too.

If anyone has any notes on whether this should be kept or not for an optimal experience please let me know. Many thanks!

What are the pros/cons of airlines selling tickets on a futures market?

Suppose the following were possible:

  • Airline stops selling seats to the general public
  • Airline advertises a route consisting of a # of seats (not necessarily any specific airplane) from a source to a destination, and offers all the seats like shares of a stock.
  • Any approved investor can buy these “shares” and sell them to other investors, or to approved travelers
  • Markets are created for investors to shoulder the risk (and reap the reward) of sold/unsold tickets.
  • This would allow airlines to smooth out volatility in booking as well as better balance their pax load. For instance, they could start with selling 50 seats from A to B 30 days from travel date. This would normally be flown using an RJ, but if demand grew subtantially, the airline could swap it with a ’37 and sell 100 more seats on the open market. This may seem to hurt original investors, but those same investors are free to buy shares in the extra 100-seat capacity. If the airline gets too greedy, they will lose because they flew a half-empty plane, so they have to be judicious in upgrading.
  • Shares (tickets) expire on the travel day, just like stock options expire on options clearing day. This means that investors must unload them on or before this date. Just like oil or corn futures. At the end, someone has to actually use them, or else the investor is out his investment, so he has to be careful to correctly gauge demand.
  • This would cause either an increasing or decreasing pattern in share prices. At first there is a higher risk that the seat will go unsold 30 days from travel date, but the longer you market the share there is more time more time for a traveler (or other investor, theoretically one shouldn’t care who buys the share) to purchase it.
  • An insurance policy would need to be created for weather or mechanical delays. This could be funded by “short-sellers” who essentially write insurance. Or else this could be funded by the airlines via a contract that a canceled flight means they must offer an equivalent “share” as soon as they possibly can, or else buy back all the shares at a very high cost.
  • “short selling” (not in the literal sense, but investors who buy an opposing instrument that obligates them to pay for a cancellation but pays them when everything is fine) would allow speculators to profit on weather forecasting while paying into (what is essentially) insurance that helps stranded travellers. “short sellers” could also speculate by buying shares near suspected blackout-dates. This might seem bad for travellers (driving costs up from speculation) but it also creates liquidity in the market and provides airlines an incentive to offer more flights. Consider that if 5% of all seats were purchased by speculators, that creates 5% extra capacity when there are weather or other cancellations. The rest of the time the capacity would be sold at the last minute, possibly at a loss.
  • Regular travellers wouldn’t notice a difference. They’d still book their flights online at the current travel sites. (or even via the airline itself, if a traveler is willing to pay X% more than an investor for the share, good for them).
  • Investors could profit by finding market inefficiencies, airlines could profit by having more guaranteed revenue for their flights. Travelers could profit by placing live orders on the open market at the price they are willing to pay (sorry for echoing the tagline of a popular travel website here). If their order is filled, they go. If they are less price-sensitive, they could put in a market order and have it filled immediately.
  • Cargo could be sold on another market, so that theoretically, a traveller might be willing to fly for half-price if they weren’t allowed a checked bag. The bag capacity would be sold to a shipping company/post office, or to another passenger who needed to take 3 bags.
  • It would create a market to “easily” start an airline. Rather, it creates a market for charter airlines to offer ‘a la carte’ routes. If there is a huge demand for travel to Hawaii in January, any properly certified carrier could sell shares on that route, and stop as soon as it’s no longer profitable. The existence of this share market might make investors less squeamish about leasing and insuring a jet and making money with it when there is a direct, standardized way to monetize the invstment.

Assuming the obvious problems are somehow taken care of (screening travellers, making sure the market is trustworthy, etc ) I see a few drawbacks right away:

  • possibly no brand association (although that could be built into the market, Delta would command a 5% premium over United or Spirit, for instance. United would have a direct financial incentive to increase customer satisfaction because they can charge more for their shares )
  • No rewards programs/credit card miles
  • A very specific procedure would have to be figured out, regarding who gets paid when a flight is cancelled. Does the traveller get $ 100 and put on the next plane ? Where does that money come from and how is it dispensed equitably.
  • ability for travellers to sit together would have to be agreed upon (whether the market handles it, or its offered in good faith by the airline, or volunteered upon by a community of travellers and software: “here’s who wants to be seated next to each other, here’s the volunteers that are willing to swap seats”).
  • Assigned seats would be difficult or impossible since the aircraft type could change. This would bother a lot of people, but a proper swapping system could be arranged. This also includes sitting in front, not wanting to be near the lavatory, etc.
  • first/business/coach class would be hard to handle. There may need to be a separate market for each class, or it could devalue 1st class because “undesirable” people may wind up lucking out and upgrading to first class cheaply. “Premium” travellers may stop using the service because of who ends up sitting next to them.
  • amateur investors could lose a lot of money. Investors would trade shares in an online brokerage,and if you bought too many shares and couldn’t unload them in time, or had to sell them at a loss, you would definitely lose money. Trading shares wouldn’t be offered to most travellers (but they could easily cancel their flight by selling them on the open market).
  • it would take a critical mass of investors/travellers for this to work. There would need to be an order book with a list of people willing to buy and sell shares at various prices. Liquidity is important.
  • it would strip airlines of side rackets like charging for bags, assigned seats, “extra legroom”, etc. I’m putting this as a negative because it takes revenue from the carrier, not because I think those rackets are good for travelers.
  • There would need to be a standardization of what constitutes an “airline”, i.e. proper passenger service. A lot of this is covered under FAA, but everything would need to be guaranteed so travellers knew they were getting a standard product.

So I’m curious if this has been considered before and what else is wrong with using this model of travel? Sorry if this is the wrong place to ask. I realize it’s more of a logistics/economics question. I just wanted to put it out there and discuss it.