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Our New Normal, Together

As the world works to mitigate the impact of the COVID-19 pandemic, our thoughts are foremost with those already ill from the virus and those on the frontlines, slowing its spread. The bravery and commitment of healthcare workers everywhere is an inspiration.

While Viget’s physical offices are effectively closed, we’re continuing to work with our clients on projects that evolve by the day. Viget has been working with distributed teams to varying degrees for most of our 20-year history, and while we’re comfortable with the tools and best practices that make doing so effective, we realize that some of our clients are learning as they go. We’re here to help.

These are unprecedented times, but our business playbook is clear: Take care of each other. We’re in this together.

Our People Team is meeting with everyone on our staff to confirm their work-from-home situation. Do they have family or roommates they can rely on in an emergency? How are they feeling physically and mentally? Do they have what they need to be productive? As a team, we’re working extra hard to communicate. Andy hosts and records video calls to answer questions anyone has about the crisis, and our weekly staff meeting schedule will continue. Recognizing that our daily informal group lunches are a vital social glue in our offices, Aubrey has organized a virtual lunch table Hangout, allowing our now fully-distributed team to catch up over video. It ensures we have some laughs and helps keep us feeling connected.

Our project teams are well-versed in remote collaboration, but we understand that not all client projects can proceed as planned. We’re doing our best to accommodate evolving schedules while keeping the momentum on as many projects as possible. For all of our clients, we’re making clear that we think long-term. We’re partners through this, and can adapt to help our clients not just weather the storm, but come through it stronger when possible. Some clients have been forced to pause work entirely, while others are busier than ever.

Viget has persevered through many downturns -- the dot com crash, 9/11, the 2008 financial crisis, and a few self-inflicted close-calls. In retrospect, it’s easy to reflect on how these situations made us stronger, but mid-crisis it can be hard to stay positive. The consistent lesson has been that taking care of each other -- co-workers, clients, partners, community peers -- is what gets us through. It motivates our hard work, it focuses our priorities and collaboration, and inspires us to do what needs to be done.

I don’t know for certain how this crisis will play out, but I know that all of us at Viget will be doing everything we can to support each other as we go through it together.



  • News & Culture

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CLI Equivalents for Common MAMP PRO and Sequel Pro Tasks

Working on website front ends I sometimes use MAMP PRO to manage local hosts and Sequel Pro to manage databases. Living primarily in my text editor, a terminal, and a browser window, moving to these click-heavy dedicated apps can feel clunky. Happily, the tasks I have most frequently turned to those apps for —starting and stopping servers, creating new hosts, and importing, exporting, deleting, and creating databases— can be done from the command line.

I still pull up MAMP PRO if I need to change a host's PHP version or work with its other more specialized settings, or Sequel Pro to quickly inspect a database, but for the most part I can stay on the keyboard and in my terminal. Here's how:

Command Line MAMP PRO

You can start and stop MAMP PRO's servers from the command line. You can even do this when the MAMP PRO desktop app isn't open.

Note: MAMP PRO's menu icon will not change color to reflect the running/stopped status when the status is changed via the command line.

  • Start the MAMP PRO servers:
/Applications/MAMP PRO.app/Contents/MacOS/MAMP PRO cmd startServers
  • Stop the MAMP PRO servers:
/Applications/MAMP PRO.app/Contents/MacOS/MAMP PRO cmd stopServers
  • Create a host (replace host_name and root_path):
/Applications/MAMP PRO.app/Contents/MacOS/MAMP PRO cmd createHost host_name root_path

MAMP PRO-friendly Command Line Sequel Pro

Note: if you don't use MAMP PRO, just replace the /Applications/MAMP/Library/bin/mysql with mysql.

In all of the following commands, replace username with your user name (locally this is likely root) and database_name with your database name. The -p (password) flag with no argument will trigger an interactive password prompt. This is more secure than including your password in the command itself (like -pYourPasswordHere). Of course, if you're using the default password root is not particular secure to begin with so you might just do -pYourPasswordHere.

Setting the -h (host) flag to localhost or 127.0.0.1 tells mysql to look at what's on localhost. With the MAMP PRO servers running, that will be the MAMP PRO databases.

# with the MAMP PRO servers running, these are equivalent:
# /Applications/MAMP/Library/bin/mysql -h 127.0.0.1 other_options
# and
# /Applications/MAMP/Library/bin/mysql -h localhost other_options

/Applications/MAMP/Library/bin/mysql mysql_options # enter. opens an interactive mysql session
mysql> some command; # don't forget the semicolon
mysql> exit;
  • Create a local database
# with the MAMP PRO servers running
# replace `username` with your username, which is `root` by default
/Applications/MAMP/Library/bin/mysql -h localhost -u username -p -e "create database database_name"

or

# with the MAMP PRO servers running
# replace `username` (`root` by default) and `database_name`
/Applications/MAMP/Library/bin/mysql -h localhost -u username -p # and then enter
mysql> create database database_name; # don't forget the semicolon
mysql> exit

    MAMP PRO's databases are stored in /Library/Application Support/appsolute/MAMP PRO/db so to confirm that it worked you can

ls /Library/Application Support/appsolute/MAMP PRO/db
# will output the available mysql versions. For example I have
mysql56_2018-11-05_16-25-13     mysql57

# If it isn't clear which one you're after, open the main MAMP PRO and click
# on the MySQL "servers and services" item. In my case it shows "Version: 5.7.26"

# Now look in the relevant MySQL directory
ls /Library/Application Support/appsolute/MAMP PRO/db/mysql57
# the newly created database should be in the list
  • Delete a local database
# with the MAMP PRO servers running
# replace `username` (`root` by default) and `database_name`
/Applications/MAMP/Library/bin/mysql -h localhost -u username -p -e "drop database database_name"
  • Export a dump of a local database. Note that this uses mysqldump not mysql.
# to export an uncompressed file
# replace `username` (`root` by default) and `database_name`
/Applications/MAMP/Library/bin/mysqldump -h localhost -u username -p database_name > the/output/path.sql

# to export a compressed file
# replace `username` (`root` by default) and `database_name`
/Applications/MAMP/Library/bin/mysqldump -h localhost -u username -p database_name | gzip -c > the/output/path.gz

  • Export a local dump from an external database over SSH. Note that this uses mysqldump not mysql.

# replace `ssh-user`, `ssh_host`, `mysql_user`, `database_name`, and the output path

# to end up with an uncompressed file
ssh ssh_user@ssh_host "mysqldump -u mysql_user -p database_name | gzip -c" | gunzip > the/output/path.sql

# to end up with a compressed file
ssh ssh_user@ssh_host "mysqldump -u mysql_user -p database_name | gzip -c" > the/output/path.gz
  • Import a local database dump into a local database
# with the MAMP PRO servers running
# replace `username` (`root` by default) and `database_name`
/Applications/MAMP/Library/bin/mysql -h localhost -u username -p database_name < the/dump/path.sql
  • Import a local database dump into a remote database over SSH. Use care with this one. But if you are doing it with Sequel Pro —maybe you are copying a Craft site's database from a production server to a QA server— you might as well be able to do it on the command line.
ssh ssh_user@ssh_host "mysql -u username -p remote_database_name" < the/local/dump/path.sql


For me, using the command line instead of the MAMP PRO and Sequel Pro GUI means less switching between keyboard and mouse, less opening up GUI features that aren't typically visible on my screen, and generally better DX. Give it a try! And while MAMP Pro's CLI is limited to the essentials, command line mysql of course knows no limits. If there's something else you use Sequel Pro for, you may be able to come up with a mysql CLI equivalent you like even better.



  • Code
  • Front-end Engineering
  • Back-end Engineering

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A Viget Glossary: What We Mean and Why it Matters - Part 1

Viget has helped organizations design and develop award-winning websites and digital products for 20 years. In that time, we’ve been lucky to create long-term relationships with clients like Puma, the World Wildlife Fund, and Privia Health, and, throughout our time working together, we’ve come to understand each others’ unique terminology. But that isn’t always the case when we begin work with new clients, and in a constantly-evolving industry, we know that new terminology appears almost daily and organizations have unique definitions for deliverables and processes.

Kicking off a project always initiates a flurry of activity. There are contracts to sign, team members to introduce, and new platforms to learn. It’s an exciting time, and we know clients are anxious to get underway. Amidst all the activity, though, there is a need to define and create a shared lexicon to ensure both teams understand the project deliverables and process that will take us from kickoff to launch.

Below, we’ve rounded up a few terms for each of our disciplines that often require additional explanation. Note: our definitions of these terms may differ slightly from the industry standard, but highlight our interpretation and use of them on a daily basis.

User Experience

Research

In UX, there is a proliferation of terms that are often used interchangeably and mean almost-but-subtly-not the same thing. Viget uses the term research to specifically mean user research — learning more about the users of our products, particularly how they think and behave — in order to make stronger recommendations and better designs. This can be accomplished through different methodologies, depending on the needs of the project, and can include moderated usability testing, stakeholder interviews, audience research, surveys, and more. Learn more about the subtleties of UX research vocabulary in our post on “Speaking the Same Language About Research”.

Wireframes

We use wireframes to show the priority and organization of content on the screen, to give a sense of what elements will get a stronger visual treatment, and to detail how users will get to other parts of the site. Wireframes are a key component of website design — think of them as the skeleton or blueprint of a page — but we know that clients often feel uninspired after reviewing pages built with gray boxes. In fact, we’ve even written about how to improve wireframe presentations. We remind clients that visual designers will step in later to add polish through color, graphics, and typography, but agreeing on the foundation of the page is an important and necessary first step.

Prototypes

During the design process, it’s helpful for us to show clients how certain pieces of functionality or animations will work once the site is developed. We can mimic interactivity or test a technical proof of concept by using a clickable prototype, relying on tools like Figma, Invision, or Principle. Our prototypes can be used to illustrate a concept to internal stakeholders, but shouldn’t be seen as a final approach. Often, these concepts will require additional work to prepare them for developer handoff, which means that prototypes quickly become outdated. Read more about how and when we use prototypes.

Navigation Testing (Treejack Testing)

Following an information architecture presentation, we will sometimes recommend that clients conduct navigation testing. When testing, we present a participant with the proposed navigation and ask them to perform specific tasks in order to see if they will be able to locate the information specified within the site’s new organization. These tests generally focus on two aspects of the navigation: the structure of the navigation system itself, and the language used within the system. Treejack is an online navigation testing tool that we like to employ when conducting navigation tests, so we’ll often interchange the terms “navigation testing” with “treejack testing”.

Learn more about Viget’s approach to user experience and research




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A Viget Glossary: What We Mean and Why It Matters - Part 2

In my last post, I defined terms used by our UX team that are often confused or have multiple meanings across the industry. Today, I’ll share our definitions for processes and deliverables used by our design and strategy teams.

Creative

Brand Strategy

In our experience, we’ve found that the term brand strategy is used to cover a myriad of processes, documents, and deliverables. To us, a brand strategy defines how an organization communicates who they are, what they do and why in a clear and compelling way. Over the years, we’ve developed an approach to brand strategy work that emphasizes rigorous research, hands-on collaboration, and the definition of problems and goals. We work with clients to align on a brand strategy concept and, depending on the client and their goals, our final deliverables can range to include strategy definition, audience-specific messaging, identity details, brand elements, applications, and more. Take a look at the brand strategy work we’ve done for Fiscalnote, Swiftdine, and Armstrong Tire.

Content Strategy

A content strategy goes far beyond the words on a website or in an app. A strong content strategy dictates the substance, structure, and governance of the information an organization uses to communicate to its audience. It guides creating, organizing, and maintaining content so that companies can communicate who they are, what they do, and why efficiently and effectively. We’ve worked with organizations like the Washington Speakers Bureau, The Nature Conservancy, the NFL Players Association, and the Wildlife Conservation Society to refine and enhance their content strategies.

Still confused about the difference between brand and content strategy? Check out our flowchart.

Style Guide vs. Brand Guidelines

We often find the depth or fidelity of brand guidelines and style guides can vary greatly, and the terms can often be confused. When we create brand guidelines, they tend to be large documents that include in-depth recommendations about how a company should communicate their brand. Sections like “promise”, “vision”, “mission”, “values”, “tone”, etc. accompany details about how the brand’s logo, colors and fonts should be used in a variety of scenarios. Style guides, on the other hand, are typically pared down documents that contain specific guidance for organizations’ logos, colors and fonts, and don’t always include usage examples.

Design System

One question we get from clients often during a redesign or rebrand is, “How can I make sure people across my organization are adhering to our new designs?” This is where a design system comes into play. Design systems can range from the basic — e.g., a systematic approach to creating shared components for a single website — all the way to the complex —e.g., architecting a cross-product design system that can scale to accommodate hundreds of different products within a company. By assembling elements like color, typography, imagery, messaging, voice and tone, and interaction patterns in a central repository, organizations are able to scale products and marketing confidently and efficiently. When a design system is translated into code, we refer to that as a parts kit, which helps enforce consistency and improve workflow.

Comps or Mocks

When reviewing RFPs or going through the nitty-gritty of contracts with clients, we often see the terms mocks or comps used interchangeably to refer to the static design of pages or screens. Internally, we think of a mock-up as a static image file that illustrates proof-of-concept, just a step beyond a wireframe. A comp represents a design that is “high fidelity” and closer to what the final website will look like, though importantly, is not an exact replica. This is likely what clients will share with internal stakeholders to get approval on the website direction and what our front-end developers will use to begin building-out the site (in other words, converting the static design files into dynamic HTML, CSS, and JavaScript code).

If you're interested in joining our team of creative thinkers and visual storytellers who bring these concepts to life for our clients, we’re hiring in Washington, D.C. Durham, Boulder and Chattanooga. Tune in next week as we decipher the terms we use most often when talking about development.




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Little Details That Matter on a Mobile Website

Oftentimes, the focus on mobile websites isn’t on adding as much information as possible or even as much detail. It’s all about making the mobile viewing experience as simple and enjoyable as the web designer possibly can. People who use their mobile devices for browsing and research do not have as much time or patience …

Little Details That Matter on a Mobile Website Read More »




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Freaky Logo Friday. Logo Mash-Ups

What would happen if the logos of famous brands suddenly wake up in the bed of another? Thats what the new tumblr blog Logo Mashups explores. It makes us think in the in the connections they share and how they are constantly appealing to our consumer mind through the commons grounds of symbology and typography.




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Wix Video — a great marketing tool for any website.

Increases time on page and boosts engagement with your site Thanks to the ever-increasing internet speeds, videos are in high demand. Right now, video is everywhere on social media, websites, and apps. We are watching them on all our screens, desktops, tablets, phones and smart TVs. It is expected a growth in video content up …

Wix Video — a great marketing tool for any website. Read More »




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Why Collaborative Coding Is The Ultimate Career Hack

Taking your first steps in programming is like picking up a foreign language. At first, the syntax makes no sense, the vocabulary is unfamiliar, and everything looks and sounds unintelligible. If you’re anything like me when I started, fluency feels impossible. I promise it isn’t. When I began coding, the learning curve hit me — hard. I spent ten months teaching myself the basics while trying to stave off feelings of self-doubt that I now recognize as imposter syndrome.




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Brighten Up Someone’s May (2020 Wallpapers Edition)

May is here! And even though the current situation makes this a different kind of May, with a new routine and different things on our minds as in the years before, luckily some things never change. Like the fact that we start into the new month with some fresh inspiration. Since more than nine years already, we challenge you, the design community, to get creative and produce wallpaper designs for our monthly posts.




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Join Our New Online Workshops On CSS, Accessibility, Performance, And UX

It has been a month since we launched our first online workshop and, to be honest, we really didn’t know whether people would enjoy them — or if we would enjoy running them. It was an experiment, but one we are so glad we jumped into! I spoke about the experience of taking my workshop online on a recent episode of the Smashing podcast. As a speaker, I had expected it to feel very much like I was presenting into the empty air, with no immediate feedback and expressions to work from.




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Smashing Podcast Episode 15 With Phil Smith: How Can I Build An App In 10 Days?

In this episode of the Smashing Podcast, we’re talking about building apps on a tight timeline. How can you quickly turn around a project to respond to an emerging situation like COVID-19? Drew McLellan talks to Phil Smith to find out. Show Notes CardMedic React Native React Native for Web Expo Apiary Phil’s company amillionmonkeys Phil’s personal blog and Twitter Weekly Update Getting Started With Nuxt Implementing Dark Mode In React Apps Using styled-components How To Succeed In Wireframe Design Mirage JS Deep Dive: Understanding Mirage JS Models And Associations (Part 1) Readability Algorithms Should Be Tools, Not Targets Transcript Drew McLellan: He is director of the full-stack web development studio amillionmonkeys, where he partners with business owners and creative agencies to build digital products that make an impact.




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Meet SmashingConf Live: Our New Interactive Online Conference

In these strange times when everything is connected, it’s too easy to feel lonely and detached. Yes, everybody is just one message away, but there is always something in the way — deadlines to meet, Slack messages to reply, or urgent PRs to review. Connections need time and space to grow, just like learning, and conferences are a great way to find that time and that space. In fact, with SmashingConfs, we’ve always been trying to create such friendly and inclusive spaces.




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DJI’s new Matrice 300 RTK drone offers a ridiculous 55-minutes of flight time and 2.7kg payload

DJI has announced their new Matrice 300 RTK “flying platform” (big drone) and the Zenmuse H20 hybrid camera series, to provide “a safer and smarter solution” to their enterprise customers. The M300 RTK, DJI says, is their first to integrate modern aviation features, advanced AI, 6-direction sensing and positioning, a UAV health management system and […]

The post DJI’s new Matrice 300 RTK drone offers a ridiculous 55-minutes of flight time and 2.7kg payload appeared first on DIY Photography.



  • DIY
  • dji
  • DJI M300 RTK
  • DJI Matrice 300 RTK
  • Matrice 300 RTK

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Photography Life makes all their paid premium courses free

Photography Life has just contributed to the selection of online courses that you can take for free. While their premim courses are normally paid $150 per course, you can now access them free of charge. The founders have released them on YouTube, available for everyone to watch. The Photography Life team came to the decision […]

The post Photography Life makes all their paid premium courses free appeared first on DIY Photography.




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Nikon has confirmed that their flagship D6 DSLR will start shipping on May 21st

It feels like forever since Nikon announced their newest flagship DSLR; the Nikon D6. It’s actually only been three months, but that hasn’t stopped some people getting anxious. Recently, customers were being told that the D6 would start shipping right about now, but now Nikon has officially come out to announce that the Nikon D6 […]

The post Nikon has confirmed that their flagship D6 DSLR will start shipping on May 21st appeared first on DIY Photography.




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Watch YouTube’s most informed sock puppet teach you how to shoot with manual exposure

For those who’ve never seen TheCrafsMan SteadyCraftin on YouTube, you’re in for a treat – even if you already understand everything contained within this 25-minute video. For those who have, you know exactly what to expect. I’ve been following this rather unconventional channel for a while now. It covers a lot of handy DIY and […]

The post Watch YouTube’s most informed sock puppet teach you how to shoot with manual exposure appeared first on DIY Photography.




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Godox’s new SL150/SL200 Mark II LED lights offer fanless “silent mode” operation

The Godox SL series LED lights have proven to be extremely popular due to their low cost. Two of the models in that range, the SL150 and SL200 have seen a Mark II update today, according to an email that Godox has been sending out today. One of the features of the new SL150II and […]

The post Godox’s new SL150/SL200 Mark II LED lights offer fanless “silent mode” operation appeared first on DIY Photography.






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eagereyesTV Episode 2: Unit Charts, Dot Plots, ISOTYPE, and What Makes Them Special

Charts usually show values as visual properties, like the length in a bar chart, the location in a scatterplot, the area in a bubble chart, etc. Unit charts show values as multiples instead. One famous example of these charts is called ISOTYPE, and you may have seen them in information graphics as well. They’re an […]




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Paper: Evidence for Area as the Primary Visual Cue in Pie Charts

How we read pie charts is still an open question: is it angle? Is it area? Is it arc length? In a study I'm presenting as a short paper at the IEEE VIS conference in Vancouver next week, I tried to tease the visual cues apart – using modeling and 3D pie charts. The big […]




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eagereyesTV: What is Data? Part 1, File Formats and Intent

We all use data all the time, but what exactly is data? How do different programs know what to do with our data? How is visualizing data different from other uses of data? And isn’t everything inside a computer data in the end? The latest episode of eagereyesTV looks at what data is and what […]




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eagereyesTV: What Is Data? Part 2, Are Images Data?

Visualization turns data into images, but are images themselves data? There are often claims that they are, but then you mostly see the images themselves without much additional data. In this video, I look at image browsers, a project classifying selfies along a number of criteria, and the additional information stored in HEIC that makes […]




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The Visual Evolution of the “Flattening the Curve” Information Graphic

Communication has been quite a challenge during the COVID-19 pandemic, and data visualization hasn't been the most helpful given the low quality of the data – see Amanda Makulec's plea to think harder about making another coronavirus chart. A great example of how to do things right is the widely-circulated Flatten the Curve information graphic/cartoon. […]




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Non-associative Frobenius algebras for simply laced Chevalley groups. (arXiv:2005.02625v1 [math.RA] CROSS LISTED)

We provide an explicit construction for a class of commutative, non-associative algebras for each of the simple Chevalley groups of simply laced type. Moreover, we equip these algebras with an associating bilinear form, which turns them into Frobenius algebras. This class includes a 3876-dimensional algebra on which the Chevalley group of type E8 acts by automorphisms. We also prove that these algebras admit the structure of (axial) decomposition algebras.




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The entropy of holomorphic correspondences: exact computations and rational semigroups. (arXiv:2004.13691v1 [math.DS] CROSS LISTED)

We study two notions of topological entropy of correspondences introduced by Friedland and Dinh-Sibony. Upper bounds are known for both. We identify a class of holomorphic correspondences whose entropy in the sense of Dinh-Sibony equals the known upper bound. This provides an exact computation of the entropy for rational semigroups. We also explore a connection between these two notions of entropy.




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Regular Tur'an numbers of complete bipartite graphs. (arXiv:2005.02907v2 [math.CO] UPDATED)

Let $mathrm{rex}(n, F)$ denote the maximum number of edges in an $n$-vertex graph that is regular and does not contain $F$ as a subgraph. We give lower bounds on $mathrm{rex}(n, F)$, that are best possible up to a constant factor, when $F$ is one of $C_4$, $K_{2,t}$, $K_{3,3}$ or $K_{s,t}$ when $t>s!$.




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A Marstrand type slicing theorem for subsets of $mathbb{Z}^2 subset mathbb{R}^2$ with the mass dimension. (arXiv:2005.02813v2 [math.CO] UPDATED)

We prove a Marstrand type slicing theorem for the subsets of the integer square lattice. This problem is the dual of the corresponding projection theorem, which was considered by Glasscock, and Lima and Moreira, with the mass and counting dimensions applied to subsets of $mathbb{Z}^{d}$. In this paper, more generally we deal with a subset of the plane that is $1$ separated, and the result for subsets of the integer lattice follow as a special case. We show that the natural slicing question in this setting is true with the mass dimension.




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On the affine Hecke category. (arXiv:2005.02647v2 [math.RT] UPDATED)

We give a complete (and surprisingly simple) description of the affine Hecke category for $ ilde{A}_2$ in characteristic zero. More precisely, we calculate the Kazhdan-Lusztig polynomials, give a recursive formula for the projectors defining indecomposable objects and, for each coefficient of a Kazhdan-Lusztig polynomial, we produce a set of morphisms with such a cardinality.




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On the finiteness of ample models. (arXiv:2005.02613v2 [math.AG] UPDATED)

In this paper, we generalize the finiteness of models theorem in [BCHM06] to Kawamata log terminal pairs with fixed Kodaira dimension. As a consequence, we prove that a Kawamata log terminal pair with $mathbb{R}-$boundary has a canonical model, and can be approximated by log pairs with $mathbb{Q}-$boundary and the same canonical model.




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Arthur packets for $G_2$ and perverse sheaves on cubics. (arXiv:2005.02438v2 [math.RT] UPDATED)

This paper begins the project of defining Arthur packets of all unipotent representations for the $p$-adic exceptional group $G_2$. Here we treat the most interesting case by defining and computing Arthur packets with component group $S_3$. We also show that the distributions attached to these packets are stable, subject to a hypothesis. This is done using a self-contained microlocal analysis of simple equivariant perverse sheaves on the moduli space of homogeneous cubics in two variables. In forthcoming work we will treat the remaining unipotent representations and their endoscopic classification and strengthen our result on stability.




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Solutions for nonlinear Fokker-Planck equations with measures as initial data and McKean-Vlasov equations. (arXiv:2005.02311v2 [math.AP] UPDATED)

One proves the existence and uniqueness of a generalized (mild) solution for the nonlinear Fokker--Planck equation (FPE) egin{align*} &u_t-Delta (eta(u))+{mathrm{ div}}(D(x)b(u)u)=0, quad tgeq0, xinmathbb{R}^d, d e2, \ &u(0,cdot)=u_0,mbox{in }mathbb{R}^d, end{align*} where $u_0in L^1(mathbb{R}^d)$, $etain C^2(mathbb{R})$ is a nondecreasing function, $bin C^1$, bounded, $bgeq 0$, $Din(L^2cap L^infty)(mathbb{R}^d;mathbb{R}^d)$ with ${ m div}, Din L^infty(mathbb{R}^d)$, and ${ m div},Dgeq0$, $eta$ strictly increasing, if $b$ is not constant. Moreover, $t o u(t,u_0)$ is a semigroup of contractions in $L^1(mathbb{R}^d)$, which leaves invariant the set of probability density functions in $mathbb{R}^d$. If ${ m div},Dgeq0$, $eta'(r)geq a|r|^{alpha-1}$, and $|eta(r)|leq C r^alpha$, $alphageq1,$ $alpha>frac{d-2}d$, $dgeq3$, then $|u(t)|_{L^infty}le Ct^{-frac d{d+(alpha-1)d}} |u_0|^{frac2{2+(m-1)d}},$ $t>0$, and the existence extends to initial data $u_0$ in the space $mathcal{M}_b$ of bounded measures in $mathbb{R}^d$. The solution map $mumapsto S(t)mu$, $tgeq0$, is a Lipschitz contractions on $mathcal{M}_b$ and weakly continuous in $tin[0,infty)$. As a consequence for arbitrary initial laws, we obtain weak solutions to a class of McKean-Vlasov SDEs with coefficients which have singular dependence on the time marginal laws.




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Almost invariant subspaces of the shift operator on vector-valued Hardy spaces. (arXiv:2005.02243v2 [math.FA] UPDATED)

In this article, we characterize nearly invariant subspaces of finite defect for the backward shift operator acting on the vector-valued Hardy space which is a vectorial generalization of a result of Chalendar-Gallardo-Partington (C-G-P). Using this characterization of nearly invariant subspace under the backward shift we completely describe the almost invariant subspaces for the shift and its adjoint acting on the vector valued Hardy space.




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Cameron-Liebler sets in Hamming graphs. (arXiv:2005.02227v2 [math.CO] UPDATED)

In this paper, we discuss Cameron-Liebler sets in Hamming graphs, obtain several equivalent definitions and present all classification results.




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Some Quot schemes in tilted hearts and moduli spaces of stable pairs. (arXiv:2005.02202v2 [math.AG] UPDATED)

For a smooth projective variety $X$, we study analogs of Quot functors in hearts of non-standard $t$-structures of $D^b(mathrm{Coh}(X))$. The technical framework is that of families of $t$-structures, as studied in arXiv:1902.08184. We provide several examples and suggest possible directions of further investigation, as we reinterpret moduli spaces of stable pairs, in the sense of Thaddeus (arXiv:alg-geom/9210007) and Huybrechts-Lehn (arXiv:alg-geom/9211001), as instances of Quot schemes.




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Nonlinear singular problems with indefinite potential term. (arXiv:2005.01789v3 [math.AP] UPDATED)

We consider a nonlinear Dirichlet problem driven by a nonhomogeneous differential operator plus an indefinite potential. In the reaction we have the competing effects of a singular term and of concave and convex nonlinearities. In this paper the concave term is parametric. We prove a bifurcation-type theorem describing the changes in the set of positive solutions as the positive parameter $lambda$ varies. This work continues our research published in arXiv:2004.12583, where $xi equiv 0 $ and in the reaction the parametric term is the singular one.




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Entropy and Emergence of Topological Dynamical Systems. (arXiv:2005.01548v2 [math.DS] UPDATED)

A topological dynamical system $(X,f)$ induces two natural systems, one is on the probability measure spaces and other one is on the hyperspace.

We introduce a concept for these two spaces, which is called entropy order, and prove that it coincides with topological entropy of $(X,f)$. We also consider the entropy order of an invariant measure and a variational principle is established.




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Resonances as Viscosity Limits for Exponentially Decaying Potentials. (arXiv:2005.01257v2 [math.SP] UPDATED)

We show that the complex absorbing potential (CAP) method for computing scattering resonances applies to the case of exponentially decaying potentials. That means that the eigenvalues of $-Delta + V - iepsilon x^2$, $|V(x)|leq e^{-2gamma |x|}$ converge, as $ epsilon o 0+ $, to the poles of the meromorphic continuation of $ ( -Delta + V -lambda^2 )^{-1} $ uniformly on compact subsets of $ extrm{Re},lambda>0$, $ extrm{Im},lambda>-gamma$, $arglambda > pi/8$.




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Approximate Two-Sphere One-Cylinder Inequality in Parabolic Periodic Homogenization. (arXiv:2005.00989v2 [math.AP] UPDATED)

In this paper, for a family of second-order parabolic equation with rapidly oscillating and time-dependent periodic coefficients, we are interested in an approximate two-sphere one-cylinder inequality for these solutions in parabolic periodic homogenization, which implies an approximate quantitative propagation of smallness. The proof relies on the asymptotic behavior of fundamental solutions and the Lagrange interpolation technique.




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Solving an inverse problem for the Sturm-Liouville operator with a singular potential by Yurko's method. (arXiv:2004.14721v2 [math.SP] UPDATED)

An inverse spectral problem for the Sturm-Liouville operator with a singular potential from the class $W_2^{-1}$ is solved by the method of spectral mappings. We prove the uniqueness theorem, develop a constructive algorithm for solution, and obtain necessary and sufficient conditions of solvability for the inverse problem in the self-adjoint and the non-self-adjoint cases




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An embedding of the Morse boundary in the Martin boundary. (arXiv:2004.14624v2 [math.GR] UPDATED)

We construct a one-to-one continuous map from the Morse boundary of a hierarchically hyperbolic group to its Martin boundary. This construction is based on deviation inequalities generalizing Ancona's work on hyperbolic groups. This provides a possibly new metrizable topology on the Morse boundary of such groups. We also prove that the Morse boundary has measure 0 with respect to the harmonic measure unless the group is hyperbolic.




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Complete reducibility: Variations on a theme of Serre. (arXiv:2004.14604v2 [math.GR] UPDATED)

In this note, we unify and extend various concepts in the area of $G$-complete reducibility, where $G$ is a reductive algebraic group. By results of Serre and Bate--Martin--R"{o}hrle, the usual notion of $G$-complete reducibility can be re-framed as a property of an action of a group on the spherical building of the identity component of $G$. We show that other variations of this notion, such as relative complete reducibility and $sigma$-complete reducibility, can also be viewed as special cases of this building-theoretic definition, and hence a number of results from these areas are special cases of more general properties.




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Lagrangian geometry of matroids. (arXiv:2004.13116v2 [math.CO] UPDATED)

We introduce the conormal fan of a matroid M, which is a Lagrangian analog of the Bergman fan of M. We use the conormal fan to give a Lagrangian interpretation of the Chern-Schwartz-MacPherson cycle of M. This allows us to express the h-vector of the broken circuit complex of M in terms of the intersection theory of the conormal fan of M. We also develop general tools for tropical Hodge theory to prove that the conormal fan satisfies Poincar'e duality, the hard Lefschetz theorem, and the Hodge-Riemann relations. The Lagrangian interpretation of the Chern-Schwartz-MacPherson cycle of M, when combined with the Hodge-Riemann relations for the conormal fan of M, implies Brylawski's and Dawson's conjectures that the h-vectors of the broken circuit complex and the independence complex of M are log-concave sequences.




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On the exterior Dirichlet problem for a class of fully nonlinear elliptic equations. (arXiv:2004.12660v3 [math.AP] UPDATED)

In this paper, we mainly establish the existence and uniqueness theorem for solutions of the exterior Dirichlet problem for a class of fully nonlinear second-order elliptic equations related to the eigenvalues of the Hessian, with prescribed generalized symmetric asymptotic behavior at infinity. Moreover, we give some new results for the Hessian equations, Hessian quotient equations and the special Lagrangian equations, which have been studied previously.




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Differentiating through Log-Log Convex Programs. (arXiv:2004.12553v2 [math.OC] UPDATED)

We show how to efficiently compute the derivative (when it exists) of the solution map of log-log convex programs (LLCPs). These are nonconvex, nonsmooth optimization problems with positive variables that become convex when the variables, objective functions, and constraint functions are replaced with their logs. We focus specifically on LLCPs generated by disciplined geometric programming, a grammar consisting of a set of atomic functions with known log-log curvature and a composition rule for combining them. We represent a parametrized LLCP as the composition of a smooth transformation of parameters, a convex optimization problem, and an exponential transformation of the convex optimization problem's solution. The derivative of this composition can be computed efficiently, using recently developed methods for differentiating through convex optimization problems. We implement our method in CVXPY, a Python-embedded modeling language and rewriting system for convex optimization. In just a few lines of code, a user can specify a parametrized LLCP, solve it, and evaluate the derivative or its adjoint at a vector. This makes it possible to conduct sensitivity analyses of solutions, given perturbations to the parameters, and to compute the gradient of a function of the solution with respect to the parameters. We use the adjoint of the derivative to implement differentiable log-log convex optimization layers in PyTorch and TensorFlow. Finally, we present applications to designing queuing systems and fitting structured prediction models.




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Triangles in graphs without bipartite suspensions. (arXiv:2004.11930v2 [math.CO] UPDATED)

Given graphs $T$ and $H$, the generalized Tur'an number ex$(n,T,H)$ is the maximum number of copies of $T$ in an $n$-vertex graph with no copies of $H$. Alon and Shikhelman, using a result of ErdH os, determined the asymptotics of ex$(n,K_3,H)$ when the chromatic number of $H$ is greater than 3 and proved several results when $H$ is bipartite. We consider this problem when $H$ has chromatic number 3. Even this special case for the following relatively simple 3-chromatic graphs appears to be challenging.

The suspension $widehat H$ of a graph $H$ is the graph obtained from $H$ by adding a new vertex adjacent to all vertices of $H$. We give new upper and lower bounds on ex$(n,K_3,widehat{H})$ when $H$ is a path, even cycle, or complete bipartite graph. One of the main tools we use is the triangle removal lemma, but it is unclear if much stronger statements can be proved without using the removal lemma.




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Convergent normal forms for five dimensional totally nondegenerate CR manifolds in C^4. (arXiv:2004.11251v2 [math.CV] UPDATED)

Applying the equivariant moving frames method, we construct convergent normal forms for real-analytic 5-dimensional totally nondegenerate CR submanifolds of C^4. These CR manifolds are divided into several biholomorphically inequivalent subclasses, each of which has its own complete normal form. Moreover it is shown that, biholomorphically, Beloshapka's cubic model is the unique member of this class with the maximum possible dimension seven of the corresponding algebra of infinitesimal CR automorphisms. Our results are also useful in the study of biholomorphic equivalence problem between CR manifolds, in question.




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Finite dimensional simple modules of $(q, mathbf{Q})$-current algebras. (arXiv:2004.11069v2 [math.RT] UPDATED)

The $(q, mathbf{Q})$-current algebra associated with the general linear Lie algebra was introduced by the second author in the study of representation theory of cyclotomic $q$-Schur algebras. In this paper, we study the $(q, mathbf{Q})$-current algebra $U_q(mathfrak{sl}_n^{langle mathbf{Q} angle}[x])$ associated with the special linear Lie algebra $mathfrak{sl}_n$. In particular, we classify finite dimensional simple $U_q(mathfrak{sl}_n^{langle mathbf{Q} angle}[x])$-modules.




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Automorphisms of shift spaces and the Higman--Thomspon groups: the one-sided case. (arXiv:2004.08478v2 [math.GR] UPDATED)

Let $1 le r < n$ be integers. We give a proof that the group $mathop{mathrm{Aut}}({X_{n}^{mathbb{N}}, sigma_{n}})$ of automorphisms of the one-sided shift on $n$ letters embeds naturally as a subgroup $mathcal{h}_{n}$ of the outer automorphism group $mathop{mathrm{Out}}(G_{n,r})$ of the Higman-Thompson group $G_{n,r}$. From this, we can represent the elements of $mathop{mathrm{Aut}}({X_{n}^{mathbb{N}}, sigma_{n}})$ by finite state non-initial transducers admitting a very strong synchronizing condition.

Let $H in mathcal{H}_{n}$ and write $|H|$ for the number of states of the minimal transducer representing $H$. We show that $H$ can be written as a product of at most $|H|$ torsion elements. This result strengthens a similar result of Boyle, Franks and Kitchens, where the decomposition involves more complex torsion elements and also does not support practical extit{a priori} estimates of the length of the resulting product.

We also give new proofs of some known results about $mathop{mathrm{Aut}}({X_{n}^{mathbb{N}}, sigma_{n}})$.




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Equivalence of classical and quantum completeness for real principal type operators on the circle. (arXiv:2004.07547v3 [math.AP] UPDATED)

In this article, we prove that the completeness of the Hamilton flow and essential self-dajointness are equivalent for real principal type operators on the circle. Moreover, we study spectral properties of these operators.