How do I make the components of a Cartier divisor again Cartier divisors?

Let $ D$ be an effective Cartier divisor on a normal noetherian scheme $ X$ . Its irreducible components are codimension $ 1$ subschemes, i.e. Weil divisors, of $ X$ but not necessarily Cartier divisors. I would like to construct a birational morphism $ f:X’ \to X$ such that the irreducible components of the pullback $ f^*D$ are Cartier divisors. If $ f$ were only an alteration, that would also be fine.

If we assume resolution of singularities, this is possible: Just choose $ f$ such that $ X’$ is regular. Then every Weil divisor is Cartier and we are done. Is there an argument avoiding resolution of singularities (and the theory of alterations)?

Ubuntu 18.04 “Bootup is not yet finished. Please try again later.” error

My Ubuntu 18.04 takes too long to boot up (about minute or so). I found that it’s possible to find out the reason using systemd-analyze, but all it gives me is Bootup is not yet finished. Please try again later. The system runs normally, but even after hour and more, the boot up is still not finished. Is there a way to find out what is not loaded?

How can access macos again?

I have macbook pro mid 2014 and I just want to install linux centos as a dual boot In selecting partition I shrink my macos drive too install linux But after installation I can’t see macos partition in startup manager I don’t know I accidentally erase my macos drive or dopid sth else Is any chance my macos still exists?

Overstayed in Schengen area, came back without issues and have to enter again

I am an Asian research student in UK. I took part in a European project so that I have to attend some short courses and do experiment in Schengen countries for a short period. I spent 2 months in Schengen area using a tourist visa from mid-April to mid of June and my visa was expired in August. I flew back to UK to apply for a new tourist visa then I got a new 2-year visa from August. After that, I went back again to continue my work in Schengen countries and spent another 2 months there. Note that. When I entered again, the border asked me how long I will stay and I said two months (As I thought that the new visa has resetted the 90/180). Then he allowed me to get in without any concerns (He should have been noticed that I will stay more than 90days within the last 180days).

When I finished my work, I came back to UK without any issues. And I just knew about 90/180 from my friend that there is not rule of resetting 90/180. According to the 90/180, I spent more than 90days within the last 180 days. So I’m a little confused that why I did not get a penalty when I passed the border or the new visa can reset the 90/180? Which one is true?

And now it has been 6 months already that I have not entered the Schengen area. What do you think if I enter the Schengen area again as I will have to visit some many strict countries (e.g. Germany, Switzerland etc.) for a meeting in the near future. Who should I contact about my situation? I’m happy to pay the penalty fee before entering the Schengen zone to make sure that I will have no problem to pass the border or with any black stamp on my passport.

Thank you very much in advance

Tencent’s Advertising Algorithm Competition launched once again as a rare chance for algorithm geeks

The 2019 Tencent Advertising Algorithm Competition officially unveiled on March 26th, inviting online registration by algorithm talents across the world which offers a rare chance for them to witness face-offs among “hardcore algorithm geeks”. Based on the successful experience of the previous two sessions,this year, Tencent Marketing Solution, or TMS, the organizer, will partner with Tencent’s leading platforms such as Tencent Big Data, Tencent Cloud, Tencent Talent, Tencent UR and TPai and join hand with Tencent’s leading data expert panel to create a feast for Advertising Algorithm. As AI, big data and cloud computing continue to “highlight” across the whole marketing process, advertisers badly need to improve their marketing efficiency and drive their business growth. To meet that need, TMS, armed with a new breed of Tencent’s smart digital tools and technologies, is here to ensure a more accurate and efficient investment by marketers. To make a real-world business scenario, TMS decides on “ad exposure forecast” or AEF, one of Tencent’s killer “Smart Services”, to be this year’s challenge. (Click the picture below to visit the official website and learn more about the challenge)

With a hardcore challenge, a real-world business scenario is prepared for you Tencent’s performance-based advertising adopts a GSP (Generalized Second-Price) bidding mechanism, where ad exposure will depend on traffic coverage and relative competitiveness in competitive ads. As an essential benchmark for advertising decisions, AEF indicates an ad’s performance in directional configuration, creative design and budget allocation. Accurate ad exposure forecasts can help advertisers shorten trial-and-error time and reduce financial costs so that expected performance level be reached quickly while quality and competitiveness of the ad platform can be improved accordingly.

Algorithm geeks across the world are invited to join With the new English access added to its official website this year, the event invites algorithm geeks from all universities and colleges, scientific research institutions and Internet companies around the world. Leveraging on AEF’s cool algorithmic wisdom, they will be challenged to tackle tough real-world advertising issues. Excellent teams and individuals in the competition will be awarded. TMS revealed that an award of 500,000 in total will be available for outstanding contestants. All participants get prizes such as mobile phones, kindles and tailored souvenirs. Contestants are encouraged to share their technical experiences, learn from weekly champions and compete for chances to have a f2f with famous algorithm experts. Top twenty teams and individuals in the semi-finals will have a direct access to Tencent’s job offers —- 2019 TMS Campus Recruitment Program (written test free). Join the competition and fly your professional dream!

Tencent’s technical expert panel will conduct reviews to facilitate technical communication In addition to the hardcore challenge applied to a real-world business scenario, this year’s competition is a great occasion for algorithm geeks to interact with Tencent’s technical experts in algorithms. Following principles of professionalism and preciseness, Tencent has enlisted a number of Tencent’s senior data experts, including General Manager of Tencent Marketing Solution Ching Law, Corporate Vice President and Director of Tencent Technical Management Committee Juliet Wang, Vice General Manager of Tencent Data Platform Department Jie Jiang, and Vice General Manager of Tencent Marketing Solution Justin Yang, to form a leading technical expert panel and communicate face-to-face with contestants in the finals.

Data intelligence drives efficiency and growth. As China’s leading marketing platform, Tencent Marketing Solution builds on Tencent’s panoramic application scenarios to turn digital assets into business value and achieve digitalization throughout the whole marketing process, covering strategy, creativity, advertising and promotion, offering a synergy of digital marketing solutions, involving brand management, promotion and retailing, online and offline. Continually updating its three core capabilities — panoramic link, whole-chain data intelligence and user-friendly experience, Tencent Marketing Solution strives to forge a smart connection between brands and their users and enable business growth and success for its clients. Tencent Marketing Solution hopes to make this competition as an open platform for global algorithm talents to share their innovative ideas and experiences while joining hands to promote a better industry development.

You’re invited to join the 2019 Tencent Advertising Algorithm Competition. To register on the official website, please scan the QR code: [enter image description here]

Please see more information via the official website of the 2019 Tencent Advertising Algorithm Competition:

Wireless disconnects and requests password again

My wifi connection is not very stable, and sometimes it goes down. When this happens, Network Manager will prompt for the wifi password, even though it is saved, correct and available.

I need to click on Cancel on the password prompt, then manually reconnect from the system tray applet, and it will connect without asking for password.

Using Kubuntu.

Is there any way to force the reconnection using the saved password? It is incredibly annoying, especially when this happens at night, right after a backup was started…


Flying from Geneva to Frankfurt to San Francisco, will my carry on bag go through the x-ray again at Frankfurt airport?

I’m planning to buy some Swiss army pocket knives as gifts at the Geneva airport (there is a store past the security check point that sells it). However, my concern is that when I am in Frankfurt, my carry on will go through the x-ray again, in which case I will not be able to carry the pocket knives with me.

So I wonder if y bag will need to go through the X ray at Frankfurt airport. Thanks!