Welcome to Semasio

Have you ever heard

of the Monty Hall problem?

Suppose you're on a game show. You have to choose one of three doors. Behind one of the doors is a car; behind the others, goats. You pick a door, lets say No. 1. The host, who knows what's behind the doors, opens one of the other doors, say No. 3, and reveals a goat beind it. He then says: "Do you want to pick door No. 2 or stick with your original choice?" Is it to your advantage to switch your choice?

The well known answer to this famous problem is that you should always switch and choose the other door. Switching improves your odds of winning from the original 1/3 to 2/3. The answer might seem like weird math, so much so that it borders on the absurd. It is nevertheless demonstrably true.

How would you show this programatically?

Write a small program to this effect and shoot us an email with your explanation. While you're at it, send us your CV too!

A little introduction

Semasio is a Germany-based tech startup that develops high-performance, low-latency software focused on infrastructure and real-time machine learning for online marketing. Our main development center is in Porto, Portugal; we have a R&D center in Aalborg, Denmark; a European HQ in Hamburg, Germany; and our North American HQ in New York, US.

We're currently looking for young and talented developers to join our Porto team!

With us you'll find:

  • Very competent colleagues
  • Interesting problems to solve that
    fuel your growth as a developer
  • Flat hierarchy and direct lines
    of communication
  • Direct and visible impact on
    the product

What we can offer:

  • Great and flexible working conditions
  • Competitive salary with lots of benefits
  • And all the other usual things – work from home, free snacks, team activities, beers in the fridge, and FIFA

Have a look at our Open Positions - maybe you'll see something there you like!

It's only online advertisement

Online advertisement is all about finding the right people to show your ads to. But how would you find your target population out of millions of unique users? And how do you guarantee that when your ads are shown, they're actually presented to someone interested in them? At Semasio, we aim to answer these questions every day, and to provide to our clients smart ways to discover their perfect audience.

So how big is the problem?

User Profiles












Data processed




Data processed



We do this everyday at Semasio

Can you help us

do it even better?

World Domination Map

* UUS = Unique Users