improve var creation for SumProdCircuit

examples/dag.rs

@@ -6,10 +6,10 @@ use circuit_cas::circuit::dag::CircuitExt;
 fn main() {
     let circuit: Rc<RefCell<ProbCircuit>> = ProbCircuit::new();
 
-    // Build (x + y) * (x + z)
-    let x = circuit.var("x");
-    let y = circuit.var("y");
-    let z = circuit.var("z");
+    // vars accept anything that implements Into<StaticVar>: &'static str, (&str, u32), (&str, u32, u32)
+    let x   = circuit.var("x");
+    let y   = circuit.var(("y", 1));       // indexed variable y_1
+    let z   = circuit.var(("z", 0, 1));    // doubly-indexed variable z_{0,1}
 
     let x_plus_y = circuit.var("x") + y;
     let x_plus_z = circuit.var("x") + z;
@@ -19,7 +19,7 @@ fn main() {
     let x2 = circuit.var("x");
     assert_eq!(x.id, x2.id);
 
-    println!("(x + y) * (x + z) root node id: {:?}", expr.id);
+    println!("(x + y_1) * (x + z_{{0,1}}) root node id: {:?}", expr.id);
     println!("x node id: {:?}", x.id);
     println!("x deduplicated node id: {:?}", x2.id);
 }

examples/quotient.rs

@@ -19,6 +19,7 @@ fn main() {
     let quotient: Rc<RefCell<QuotientCircuit>> = idem.into();
 
     // Build x * x̄ + x in the DAG
+    // var accepts anything that implements Into<StaticVar>: &'static str, (&str, u32), (&str, u32, u32)
     let xn   = quotient.var("x");
     let nxn  = quotient.var("x\u{0304}");
     let prod = xn * nxn;