@@ 424,7 424,7 @@ the first boundaries in the list should be that of the 1-simplices.
         simplices = ordered_simplices;
     }
 
-    let mut persistence = Persistence {
+    let persistence = Persistence {
         simplices,
         points: points.unwrap_or(Vec::new()),
         alphas: alphas.unwrap_or(Vec::new()),

@@ 10,8 10,6 @@ pub enum Variant {
     /// The exhaustive variant tries to lower the indices of the reduces simplcides after the max
     /// has been found.
     Exhaustive,
-    /// It's not clear why this is interesting?
-    ExhaustiveWhenD1,
 }
 use self::Variant::*;
 


@@ 149,6 147,7 @@ pub fn reduce(p: &Persistence, variant: Variant, _stats: &mut Statistics) -> Red
     let mut reduced_with_low: Vec<Option<Simplex>> = vec![None; p.simplices.len()];
     // We're reducing each simplex.
     for simplex in &p.simplices {
+        // we'll store an index here, if we don't fully reduce the simplex
         let mut place_index = None;
         // With no boundary we're done.
         if simplex.faces.last().is_none() {


@@ 158,30 157,27 @@ pub fn reduce(p: &Persistence, variant: Variant, _stats: &mut Statistics) -> Red
         current_reduced.faces.sort();
 
         while current_reduced.faces.len() > 0 {
-            let low: usize = *current_reduced.faces.last().unwrap();
-            match reduced_with_low[low] {
-                None => {
-                    place_index = Some(low);
-                    break;
-                }
-                Some(ref other) => {
-                    simplex_reduce(&mut current_reduced, other);
-                }
+            let low = *current_reduced.faces.last().unwrap();
+            if let Some(ref other) = reduced_with_low[low] {
+                simplex_reduce(&mut current_reduced, other);
+            } else {
+                place_index = Some(low);
+                break;
             }
         }
 
         if variant == Exhaustive {
             // Reduce the rest of the simplex. Go backwards. We can skip the last index, since
-            // that's us. Then we count the numbers of boundary simplices we know we can't reduce any
-            // further. Since we're going bottom up and looking at `reduced_with_low`, these cannot
-            // change with later redutions.
+            // that's us. Then we count the numbers of boundary simplices we know we can't reduce
+            // any further. Since we're going bottom up and looking at `reduced_with_low`, these
+            // cannot change with later redutions.
             let mut safe_simplices = 1;
-            let mut faces = current_reduced.faces.len();
-            while faces > safe_simplices {
-                let cand_i = current_reduced.faces[faces - 1 - safe_simplices];
+            let mut n = current_reduced.faces.len();
+            while safe_simplices < n {
+                let cand_i = current_reduced.faces[n - 1 - safe_simplices];
                 if let Some(ref cand) = reduced_with_low[cand_i] {
                     simplex_reduce(&mut current_reduced, cand);
-                    faces = current_reduced.faces.len();
+                    n = current_reduced.faces.len();
                 } else {
                     safe_simplices += 1;
                 }


@@ 189,7 185,9 @@ pub fn reduce(p: &Persistence, variant: Variant, _stats: &mut Statistics) -> Red
         }
 
         if current_reduced.faces.len() != 0 {
-            let i = place_index.expect("Reduced simplex isn't empty, yet we haven't set the index in which to store it");
+            let i = place_index.expect(
+                "Reduced simplex isn't empty, yet we haven't set the index in which to store it",
+            );
             reduced_with_low[i] = Some(current_reduced);
         }
     }


@@ 249,51 247,6 @@ fn simplex_reduce(this: &mut Simplex, other: &Simplex) {
     }
 }
 
-/// Add the `other` column into the `this` column. Since we're in (mod 2) arithmetic, this `xor`s
-/// together the two vectors.
-fn column_add(
-    this: &mut Vec<usize>,
-    other: &Vec<usize>,
-    simplex_dim: usize,
-    stats: &mut Statistics,
-) {
-    // TODO: hehe
-    static mut BUFFER: Option<Vec<usize>> = None;
-    let buffer: &mut Vec<usize> = unsafe {
-        if BUFFER.is_none() {
-            BUFFER = Some(Vec::with_capacity(1_000));
-        }
-        BUFFER.as_mut().unwrap()
-    };
-    debug_assert_eq!(buffer.len(), 0);
-    stats.col_add(simplex_dim);
-    stats.add_sizes(this.len(), other.len());
-
-    let mut our_i = 0;
-    let mut their_i = 0;
-    let our_last = this.len();
-    let their_last = other.len();
-
-    while our_i < our_last && their_i < their_last {
-        if this[our_i] < other[their_i] {
-            buffer.push(this[our_i]);
-            our_i += 1;
-        } else if this[our_i] == other[their_i] {
-            our_i += 1;
-            their_i += 1;
-        } else {
-            buffer.push(other[their_i]);
-            their_i += 1;
-        }
-    }
-
-    buffer.extend(&other[their_i..]);
-    buffer.extend(&this[our_i..]);
-    this.clear();
-    this.extend(&*buffer);
-    buffer.clear();
-}
-
 /// Compute the alpha values for the simplices, given the point location.
 /// As the name suggests, this is only for dimension 2 and less.
 pub fn compute_alpha_values_2d(