flag-algebra

An implementation of flag algebras.

Example

extern crate flag_algebra;

use flag_algebra::*;
use crate::sdp::Problem;
use crate::flags::Graph;
use crate::operator::Basis;

pub fn main() {
   // Work on the graphs of size 3.
   let basis = Basis::new(3);

   // Define useful flags.
   let k3 = flag(&Graph::new(3, &[(0,1),(1,2),(2,0)])); // Triangle
   let e3 = flag(&Graph::new(3, &[])); // Independent set of size 3

   // Definition of the optimization problem.
   let pb = Problem::<i64, _> {
       // Constraints
       ineqs: vec!(total_sum_is_one(basis),
                   flags_are_nonnegative(basis)),
       // Use all relevant Cauchy-Schwarz inequalities.
       cs: basis.all_cs(),
       // Minimize density of triangle plus density of independent of size 3.
       obj: k3 + e3,
   };

   // Write the correspondind SDP program in "goodman.sdpa".
   // This program can then be solved by CSDP.
   pb.write_sdpa("goodman").unwrap();
}

License: GPL-3.0