Facebook opened an office in seattle, with a puzzle

Disclaimer. I don't like many puzzles, unless there is some math or algorithm intuition behind them. So, Facebook is going to Seattle and they have a puzzle. Here it is. 

Let's see: 

The first occurrence of 'e' comes before 1 occurrence of 's'.
The first occurrence of 'i' comes before 1 occurrence of 'n'.
The first occurrence of 'i' comes before 1 occurrence of 'i'.
The first occurrence of 'n' comes before 2 occurrences of 'e'.
The first occurrence of 'e' comes before 1 occurrence of 'e'.
The first occurrence of 'i' comes before 1 occurrence of 'v'.
The first occurrence of 'n' comes before 1 occurrence of 'i'.
The first occurrence of 'n' comes before 1 occurrence of 'v'.
The first occurrence of 'i' comes before 1 occurrence of 's'.
The first occurrence of 't' comes before 1 occurrence of 's'.
The first occurrence of 'v' comes before 1 occurrence of 's'.
The first occurrence of 'v' comes before 2 occurrences of 'e'.
The first occurrence of 't' comes before 2 occurrences of 'e'.
The first occurrence of 'i' comes before 2 occurrences of 'e'.
The first occurrence of 'v' comes before 1 occurrence of 't'.
The first occurrence of 'n' comes before 1 occurrence of 't'.
The first occurrence of 'v' comes before 1 occurrence of 'i'.
The first occurrence of 'i' comes before 1 occurrence of 't'.
The first occurrence of 'n' comes before 1 occurrence of 's'

• What is the dictionary of distinct letters? This is given by the symbols used for the above rules. Therefore: i, n, e, v, t, s, 
• Are there repetitions? yes, "2 occurrences of e" and "2 occurrences of i". So the letters are D={i, n, e, v, t, s, e, i} and the string has length 7 because all the rules are given
• So the solution is an anagram of D which respects the rules

I am too lazy to test all the rules, let's test the solution directly 

http://www.facebook.com/seattle/invitees/