# Calling All Nodes: Join Us for Global Graph Celebration Day – April 15, 2020!

What Is Global Graph Celebration Day?

To honor Leonhard Euler, the Swiss mathematician and inventor of graph theory, the Neo4j community and graph-enthusiasts all over the world gather and host events to celebrate the day of his birth, April 15th.

Last year was the first official GGCD. This monumental day fostered more than 60 events in six continents! Browse through some of the photos from last year!

Interested in being a GGCD 2020 organizer? Sign-up below for more info!

### A Brief “History of Leonhard Euler and Graph Theory” Lesson

Thanks to Wikipedia, here’s a synopsis of Euler’s fascinating story:

Leonhard Euler (pronounced ‘OY-lər) is a Swiss mathematician, physicist, astronomer, logician and engineer. He is responsible for some of the most influential mathematical discoveries, including graph theory.

In 1735, Euler presented a solution to the problem known as the Seven Bridges of Königsberg. The city of Königsberg, Prussia was set on the Pregel River, and included two large islands that were connected to each other and the mainland by seven bridges. The problem is to decide whether it is possible to follow a path that crosses each bridge exactly once and returns to the starting point. It is not possible: there is no Eulerian circuit. This solution is considered to be the first theorem of graph theory, specifically of planar graph theory.

Euler also discovered the formula V-E+F=2 relating the number of vertices, edges and faces of a convex polyhedron, and hence of a planar graph. The constant in this formula is now known as the Euler characteristic for the graph (or other mathematical object), and is related to the genus of the object. The study and generalization of this formula, specifically by Cauchy and L’Huilier, is at the origin of topology.

Graphs are instrumental in many areas within our current society, including in technology, where we can see a trend from the steep adoption of graph databases.

But don’t take it from me! Here’s a chart taken from DB-Engines.com:

Last year, we made a 10-minute GGCD video highlighting some of the ways graph databases are being applied in our world today:

As we get geared up for its second year, we invite our community to participate with us in this movement. Here’s how:

• Organize your own local event with friends and colleagues.
• Offer to present or help organize alongside one of your local meetups or community groups.
• Participate as an attendee at one of your local GGCD events.

### What Kind of Events Qualify?

The only requirements are that all events are graph-y in theme and occur on April 15th. Your event can be any size, occur at any time of the day, be public or private, and have any kind of activities you think would be fun!

Here are some ideas from last year:

• Collaborate with a local meetup group: Offer to do a presentation or lead an intro to graph databases workshop.
• Host a hackathon: Pick some topics and build graphy-projects with your friends.
• Graph Games: See who on your team gets the farthest with laptop games like Treksit, break into groups and play Pandemic Board Game, or go simple with pencil-and-paper games like, Sim, Achi or Sprouts!
• Whiteboard Brainstorm: Pick a topic(s) and organize a graph-modeling whiteboard brainstorming session. (Or, gamify it as a “speed-graph” contest where you announce any random topic and users have two minutes to model a graph.)
• Neo4j Sandbox Discovery Game: Have friends log on to Neo4j Sandbox and see if they make any interesting discoveries.
• Google Mini-Map: Everyone exports their Google maps data and graphs it to see if they overlapped.
• Watch some educational videos from NODES 2019: Neo4j Online Developer Expo & Summit (NODES 2019) has some really strong content!

### The GGCD Community Graph!

We’ll be making an open community graph of all the events, their attendees, their jobs, hobbies and interests!

As an organizer, you can register your event to get listed on GlobalGraphCelebrationDay.com and get added to the graph!

You’ll also get a custom RSVP URL to get your attendees added to the graph!

### How Will Neo4j Help?

Upon signing up in the email form below, you’ll receive an email from the Neo4j Developer Relations Team. This email will provide you with a basic rundown of planning your celebration, as well as a contact for resources you may need along the way.

Once you register your event with us, we will:

1. List your event on GlobalGraphCelebrationDay.com
2. Provided you with a custom RSVP url to add your event and attendees to the community graph
3. Ship you a box of Global Graph Celebration Day t-shirts for you and your attendees (*limited to first 1200 RSVP’s)! We’ll also include a little special gift for the organizers!
4. Extend an exclusive invite to the Ecosystem Summit (private event for Neo4j community contributors) at GraphConnect 2020 in NYC.
5. Include the picture from your event on the Neo4j Global Graph Celebration Day recap blog post!
6. Bonus: we can’t promise this, but there’s a possibility of having your event picture shown during the GraphConnect 2020 keynote by Neo4j CEO Emil Eifrem (will be available for viewing via live stream)
Here’s a sneak peak of our shirts this year. Yes, these shirts have a never-ending cypher query on them! 😀