Artisanal Handcrafted Ontologies

Macrame_OwlsHere at Thetus, we use the OWL Web Ontology Language to create our semantic knowledge models. Engineers working with OWL typically edit their models with tools like Protégé or TopBraid Composer, but sometimes you want or need to create a model by hand.  Semantic Modelers at Thetus often edit ontologies by hand because our knowledge modeling engine, Publisher, uses our own in-house OWL serialization syntax, known as Thetus Markup Language (TML).  TML is an XML syntax that was created as a friendlier alternative to RDF/XML.

Maintaining a proprietary serialization syntax and the toolchain to support it is a lot of work, so we’ve begun to consider alternatives.  As the Semantic Web has matured, many serialization syntaxes for RDF and OWL have been proposed, and choosing one can be a little overwhelming.  For handcrafted ontologies, many Semantic Web veterans recommend using Turtle, but they don’t often explain why it’s the best choice.  Working with our own syntax has given modelers at Thetus some strong opinions about what we were looking for in a new one, and since we weren’t very familiar with many of the available syntaxes, we decided to do some research and draw our own conclusions.

The modeling team at Thetus reviewed about a dozen syntaxes for this effort: the OWL Functional Syntaxes, OWL/XML, RDF/XML, Manchester Syntax, Turtle, N-Triples, JSON-LD, Notation 3 (N3), TriG, TriX, and N-Quads.  With the help of various syntax conversion tools, we converted some ontologies we’ve worked with to each of these syntaxes so we could assess their readability.  We also spent a lot of time reviewing the documentation for each syntax and scouring the web for expert opinions on them.  We developed a set of criteria for evaluating syntaxes, and then weighted the criteria and ranked them.


Click to expand serialization decision matrix

Our criteria for editing models by hand fell into two main categories. First, the syntax should be easy for humans to read and write. Specifically, during the review, four human-friendly qualities stood out in particular:

  1. The syntax provides an alternative to using absolute IRIs, such as namespace prefixes or relative IRIs.
  2. The syntax doesn’t force the author to write flat triples, offering features such as inline or nested blank nodes, collections, or lists.
  3. The syntax provides a shorthand for literals and common predicates.
  4. The syntax is not XML, as many people do not enjoy typing numerous angle brackets.

Second, the syntax should have good support from existing Semantic Web tools, such as Apache Jena, the OWL API and various RDF and OWL conversion tools, because you don’t want to invest a lot of effort into building a model only to find that existing tools can’t read it. Since we were focused on hand-editing models, we didn’t take into consideration whether Protégé or TopBraid Composer supported the syntaxes.

Given the human-friendly qualities above, it became easy to rule out several syntaxes immediately.  We learned that four of the syntaxes are closely related: Turtle, N3, N-Triples and TriG, which we began to refer to collectively as the Turtle family. Of the Turtle family, N-Triples lacks the first three qualities, so it was easy to rule out.

Of the other syntaxes, N-Quads also lacks the first 3 qualities. OWL/XML and TriX don’t do so well on the second quality because they lack nesting features.  All three of the normative syntaxes (OWL Functional, OWL/XML and RDF/XML) lack shorthand features.  OWL/XML, RDF/XML, and TriX were further ruled out because they are all XML formats. And if avoiding XML is important, JSON-LD also starts to look less attractive, because it requires typing lots of curly braces and is somewhat verbose.

This leaves us with three of the four Turtle family syntaxes—Turtle, N3, TriG—and the Manchester Syntax.  In our weighted ranking, they were in a four-way tie for first place across the human-friendly ease of use qualities, with good support for all four of our desired qualities and only minor differences in their coverage of the third quality.

We used our second main category of criteria—tool support—to break this tie, which is how Turtle ended up leading the pack.  It has the most support of any serialization syntax other than RDF/XML , which is the only syntax that OWL 2 tools are required to support.  Additionally, if you are a SPARQL user, familiarity with Turtle is useful because it has a great deal of overlap with the syntax of SPARQL’s WHERE clause.

So now you know why Thetus thinks Turtle is the best syntax for writing ontologies by hand! What do you think?

~ Marijane White, Principal Engineer

Savanna 4.1 Has Arrived

With a collective sigh and a rush of engineers to the keg, the latest release of Savanna 4.1 headed out the door. As with every new Savanna release, we’ve added even more features to make your analysis experience fun and effective.

There were numerous enhancements to a variety of features in this release, but we’ll focus on two of our major enhancements: taggable Occurrences and heatmap visualizations.

Occurrence: Dynamic Documents for Dynamic Data

4.1 Blog - Occurrence 2
In 4.1, Savanna’s Occurrence tool continues to allow analysts to create connected information networks by capturing detailed, problem-specific information about people, organizations, places and events within dynamic documents. For example, you might make a Person Occurrence to gather information about the current Portland Mayor, or a Place Occurrence for Portland City Hall.

Because data isn’t always easily defined or categorized, Occurrences now allow analysts to customize information beyond the basic data fields.

Here are two of our new key customization tools:

  • 4.1 Blog - Description 3Descriptions: Now you can add fine-grained detail to your Occurrences by entering new description names and types to capture and easily find specifics about your Occurrences. For example, you could add a physical description to your Portland City Hall Occurrence and fill in information from a specific article or website.



  • 4.1 Blog - TagTags: Tags quickly reveal important keywords or phrases about an Occurrence. With the new tags fields, you can easily capture categories of an Occurrence that might not be available in a given template. For example, an analyst might make an Architectural Style tag name, and then fill in “Italian Renaissance” as the associated style.


These customizable options allow you to make the most of your data, giving you the ability to capture hard-to-define information and build interconnected networks for holistic analysis.

Map: Introducing a Hot New Feature (pun entirely intended)

Maps are everywhere, and digital maps are as commonly used today as atlases were in the 90’s (an atlas, if you remember, is a map depicted on paper). It’s important then that a map does more than show you how to get from point A to point B. Savanna’s Map tool geospatially visualizes data from any integrated or constructed standard open geospatial formats, with content filtering and visibility settings that allow you to quickly view the most relevant information.

4.1’s heatmap enhancement allows you to capture and view trends in specific Map regions, giving you a bird’s eye view of your data that is customizable by radius, display color and opacity.

4.1 Blog - Heatmap 2
You can keep up with upcoming releases and new features here on our blog and in the meantime keep yourself entertained by watching Savanna in action on our YouTube page at Until next time.

Metadata: Data That Describes Data

Say you need a chair and your friend has one that he would be happy to give you. Before you agree to haul it away in a borrowed pick-up, you want to know more about the chair. Is it comfortable? Is it hard to clean? Will it match your décor? Is it the right size for your space?

So you ask your friend a few questions to get more information. What kind of upholstery does the chair have? How long is it? Does it recline? What color is it? All of these questions are meant to provide context for you to decide whether the chair suits your needs. In other words, you are gathering data about the chair. If you think of the chair as a single piece of data (or stated another way, as a data set containing just one record), then the description of the chair is its metadata. Put simply, metadata is data about data.

Ron_Arad_-_The_Big_Easy_chair_in_chrome_steelWhether your data is a physical object, a digital file, or a row in a spreadsheet, metadata is necessary to understand the value, function, and history of your data. If you learned that your friend’s chair was the Ron Arad Big Easy Chair (image at left) you might think twice before taking it. More realistically, you might learn that the chair is a reclining chair, vinyl upholstery, and is 84” wide.

Similarly, imagine reading an undated news article about an outbreak of a deadly disease in a nearby city. Without knowing the article’s publication date, you wouldn’t know if the outbreak is spreading rapidly or if it occurred 20 years ago! Suppose you later learn that the article came from The Onion, a satirical newspaper. You would then assume the article is exaggerated or untrue.

Metadata grows in importance with the quantity of data under consideration. If you have 100,000 chairs to choose from, you need ways to differentiate between them without examining each individually. Identifying metadata common to many chairs would help distinguish collections of like data within your data set. For instance, you might only be interested in recliners or accent chairs. Many chairs will fall into multiple collections, leaving it up to you to decide which are of primary importance.

Savanna, Thetus’s multi-source analysis solution, incorporates metadata throughout the analysis workspace. Users can capture details about people, organizations, places, and concepts in preformatted metadata fields or freeform narratives. Options for describing connections between different types of data allow for easy identification of related content. Privacy settings specify rules about who can access specific data. Cumulatively, Savanna’s metadata tools enable users to contextualize information and thus reap greater insight into complex problems.

Different types of metadata gain prominence depending on the user and what kind of information they need. You asked your friend questions relevant to a chair but your query would have been different if you were discussing a song, a map, or a car. Similarly, different Savanna users present varied forms of information relevant to their problem space. A geospatial analyst in the military assessing locations of weapons stockpiles cares about different data—and thus metadata—than an emergency planner assessing earthquake hazard mitigation strategies. In most cases, users have predefined metadata based on organizational or disciplinary standards.

Regardless of users’ specific needs, the importance of metadata remains. Metadata can be simple and intuitive, as when thinking about the characteristics of a couch, or it can be formalized, detailed, and discipline-specific. Given the potential for metadata to profoundly influence your interpretation of information, you should treat metadata as an integral part of any data set.

~ Rebecca Davies, Analyst


“Metadata Guide Working Level.” Australian National Data Service. June, 2011. Accessed December 29, 2014.

Image Source: “Ron Arad – The Big Easy chair in chrome steel” by Ron Arad – Own work. Licensed under CC BY 3.0 via Wikimedia Commons –

Flat Design

You know the old saying ‘less is more?’ That seems to be the mantra for the current trend in user interface design. We’re seeing less and less of the 3D object design and more flat design. Less clutter, less fuss and more openness are becoming the norm. And now the trend has been solidified with Apple’s recent iOS7 release.

Apple's 3D design compared to their new flat design

Apple’s 3D design compared to their new flat design

But with simplicity comes a great deal of consideration, without the bells and whistles (gradients, drop shadows etc) the focus is solely on the shapes and color choices of the design. With less text, the design needs to visually explain itself but with a minimal design approach. Have we become so familiar with digital user interfaces that the need to create 3D design to emulate real-world objects is a thing of the past? Or is this cleaner approach to design just another trend?

Thetus Savanna Webcast Tomorrow!

Register to view our webcast tomorrow! 

Wednesday, October 23rd at 11am PST/ 2pm EST

Discover how Savanna, our all-source analysis suite, helps make sense of information and pivots data as new knowledge evolves so you can turn insight into a solution.


Tech Economy Summit Events

taoWe’re excited to host two networking events leading up to a summit called Portland State of Mind: Powering the Region’s Tech Economy this week.  Portland State of Mind, a joint summit between Portland State University and the Technology Association of Oregon, will focus on the needs of the Oregon tech industry and PSU’s role in supporting those needs, including research and development, workforce training, and economic development.

PSU_white_screenAmong the events is CleanWeb Hack, a hack-a-thon hosted at PSU with CleanWeb on Saturday, October 26 that will bring together students and professionals from different disciplines to solve environmental issues through utilization of information technology. Participants will spend one day hacking in small teams to create radical new solutions across issues related to climate change and global resource constraints and will present their creations to a panel of judges on Saturday evening. This is also a “tech laboratory” where students will work alongside professionals to apply their knowledge. The U.S. Department of Energy’s datasets that will be available to attendees include datasets pertaining to energy, solar, and utility rates.

cleanweb_mainlogo_temporaryWe’ll be hosting the pre-event networking happy hour leading up to the CleanWeb Hack in our Portland Headquarters. The happy hour is on Wednesday, October 23rd from 5:30pm to 7:30pm and will serve as an opportunity for those participating in the hack to meet each other and form teams.

Register for the CleanWeb Hack event 

On Thursday, October 24th we’ll be hosting a pre-event networking happy hour for the Portland tech community. This happy hour will serve as the meet and greet event leading up to Friday, October 25th’s executive discussion of the needs of the tech sector, and how PSU can best support them.  Stephen Fleming, Vice President at Georgia Tech’s Enterprise Innovation Institute, will keynote this event and share lessons that can be learned from a national model of successful industry-university partnerships.

This Friday morning event is free to attend but registration is required.

Thetus South is Now in Business

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Aren’t those big windows amazing!

We’ve got our headquarters in Portland, Oregon, our business development office in Washington, D.C. and now we’re proud to announce we’ve opened an office in Music City!  Located in the heart of Nashville’s historic arts district, the newest addition to the Thetus family embodies the classic Thetus feel while creating its own identity in unique and historic Cummins Station.

Originally built in 1907 , Cummins Station is famous for once being the warehouse for Maxwell House Coffee.  Over a century later, it’s making a new mark on Nashville as a fabulous and creative LEED Gold mixed-use space.  Home to over 140 businesses including restaurants, architecture firms, IT companies, a gym, and even a tattoo parlor, the 400,000 square feet house a community dedicated to environmental sustainability and corporate citizenship – a perfect match for Thetus!

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We also make sure to have an open floor plan.

We did some slight enhancement work to restore the space’s original character –  we repainted the walls, got rid of the paint on the brick (thank goodness), ripped up the carpet and put a clear epoxy finish on the original concrete floor, we added shelving of scrap wood to provide extra storage and added glass to the conference walls for more natural light .We’re happy to call it home!

Screen Shot 2013-10-14 at 4.54.17 PMWe are actively recruiting in Nashville, and we look forward to adding some fabulous new members to our Thetus South team, and becoming part of an exceptional new community! To see our open positions visit our site.

To jump start our community involvement in Nashville we’re sponsoring this weekend’s Hack Nashville. If you’re in the area, join the 48-hours of coding fun!


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