diff --git a/autoprecompiles/src/optimizer.rs b/autoprecompiles/src/optimizer.rs
index 48275edc6..ce94c7115 100644
--- a/autoprecompiles/src/optimizer.rs
+++ b/autoprecompiles/src/optimizer.rs
@@ -142,7 +142,7 @@ pub fn optimize_exec_bus<T: FieldElement>(
                 .iter()
                 .map(|arg| {
                     let mut arg = arg.clone();
-                    powdr::substitute_algebraic_algebraic(&mut arg, &subs);
+                    powdr::substitute_subexpressions(&mut arg, &subs);
                     simplify_expression(arg)
                 })
                 .collect();
@@ -170,14 +170,14 @@ pub fn optimize_exec_bus<T: FieldElement>(
     machine.bus_interactions.push(latest_send.unwrap());
 
     for c in &mut machine.constraints {
-        powdr::substitute_algebraic_algebraic(&mut c.expr, &subs);
+        powdr::substitute_subexpressions(&mut c.expr, &subs);
         c.expr = simplify_expression(c.expr.clone());
     }
     for b in &mut machine.bus_interactions {
-        powdr::substitute_algebraic_algebraic(&mut b.mult, &subs);
+        powdr::substitute_subexpressions(&mut b.mult, &subs);
         b.mult = simplify_expression(b.mult.clone());
         for a in &mut b.args {
-            powdr::substitute_algebraic_algebraic(a, &subs);
+            powdr::substitute_subexpressions(a, &subs);
             *a = simplify_expression(a.clone());
         }
     }
diff --git a/autoprecompiles/src/powdr.rs b/autoprecompiles/src/powdr.rs
index 097e50295..b95c33cc2 100644
--- a/autoprecompiles/src/powdr.rs
+++ b/autoprecompiles/src/powdr.rs
@@ -1,4 +1,4 @@
-use std::collections::{BTreeMap, BTreeSet};
+use std::collections::BTreeMap;
 use std::sync::Arc;
 
 use itertools::Itertools;
@@ -8,20 +8,6 @@ use powdr_number::FieldElement;
 use crate::expression::{AlgebraicExpression, AlgebraicReference};
 use crate::SymbolicMachine;
 
-// After powdr and lib are adjusted, this function can be renamed and the old substitute removed
-pub fn substitute_algebraic<T: Clone>(
-    expr: &mut AlgebraicExpression<T>,
-    sub: &BTreeMap<AlgebraicReference, AlgebraicExpression<T>>,
-) {
-    expr.pre_visit_expressions_mut(&mut |expr| {
-        if let AlgebraicExpression::Reference(r) = expr {
-            if let Some(sub_expr) = sub.get(r) {
-                *expr = sub_expr.clone();
-            }
-        }
-    });
-}
-
 pub fn make_refs_zero<T: FieldElement>(expr: &mut AlgebraicExpression<T>) {
     let zero = AlgebraicExpression::Number(T::zero());
     expr.pre_visit_expressions_mut(&mut |expr| {
@@ -36,18 +22,7 @@ pub fn make_bool<T: FieldElement>(expr: AlgebraicExpression<T>) -> AlgebraicExpr
     expr.clone() * (expr - one)
 }
 
-pub fn has_ref<T: Clone + std::cmp::PartialEq>(
-    expr: &AlgebraicExpression<T>,
-    r: &AlgebraicExpression<T>,
-) -> bool {
-    expr.all_children().any(|expr| expr == r)
-}
-
-pub fn is_ref<T: Clone>(expr: &AlgebraicExpression<T>) -> bool {
-    matches!(expr, AlgebraicExpression::Reference(_))
-}
-
-pub fn substitute_algebraic_algebraic<T: Clone + std::cmp::Ord>(
+pub fn substitute_subexpressions<T: Clone + std::cmp::Ord>(
     expr: &mut AlgebraicExpression<T>,
     sub: &BTreeMap<AlgebraicExpression<T>, AlgebraicExpression<T>>,
 ) {
@@ -58,21 +33,6 @@ pub fn substitute_algebraic_algebraic<T: Clone + std::cmp::Ord>(
     });
 }
 
-// After powdr and lib are adjusted, this function can be renamed and the old collect_cols removed
-pub fn collect_cols_algebraic<T: Clone + Ord>(
-    expr: &AlgebraicExpression<T>,
-) -> BTreeSet<AlgebraicExpression<T>> {
-    expr.all_children()
-        .filter_map(|expr| {
-            if let AlgebraicExpression::Reference(..) = expr {
-                Some(expr.clone())
-            } else {
-                None
-            }
-        })
-        .collect()
-}
-
 pub trait UniqueReferences<'a, T: 'a> {
     /// Returns an iterator over the unique references
     fn unique_references(&'a self) -> impl Iterator<Item = AlgebraicReference>;