diff --git a/crates/ascend/src/models.rs b/crates/ascend/src/models.rs
index 8ddc100..272969b 100644
--- a/crates/ascend/src/models.rs
+++ b/crates/ascend/src/models.rs
@@ -8,7 +8,6 @@ pub use v2::ImageFilename;
 pub use v2::ImageResolution;
 pub use v2::ImageUid;
 pub use v2::Method;
-pub use v2::Problem;
 pub use v2::ProblemUid;
 pub use v2::Root;
 pub use v2::Wall;
@@ -17,13 +16,45 @@ pub use v2::WallUid;
 pub use v3::Attempt;
 pub use v3::UserInteraction;
 pub use v4::DatedAttempt;
+pub use v4::Problem;
+pub use v4::ProblemHolds;
 
 mod semantics;
 
 pub mod v4 {
+    use super::v1;
+    use super::v2;
     use super::v3;
     use chrono::DateTime;
     use chrono::Utc;
+    use serde::Deserialize;
+    use serde::Serialize;
+    use std::collections::BTreeMap;
+    use std::collections::BTreeSet;
+
+    #[derive(Serialize, Deserialize, Debug, Clone)]
+    pub struct Wall {
+        pub uid: v2::WallUid,
+        pub wall_dimensions: v2::WallDimensions,
+        pub holds: BTreeMap<v1::HoldPosition, v2::Hold>,
+        pub problems: BTreeSet<Problem>,
+    }
+
+    #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
+    pub struct Problem {
+        pub holds: ProblemHolds,
+        pub method: v2::Method,
+        pub transformation: Transformation,
+    }
+
+    #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Copy)]
+    pub struct Transformation {
+        pub horizontal_shift: u64,
+        pub mirror: bool,
+    }
+
+    #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
+    pub struct ProblemHolds(pub BTreeMap<v1::HoldPosition, v1::HoldRole>);
 
     #[derive(Debug, Clone, Copy)]
     pub struct DatedAttempt {
@@ -93,7 +124,7 @@ pub mod v2 {
         pub problems: BTreeSet<ProblemUid>,
     }
 
-    #[derive(Debug, Copy, Clone, PartialEq, Eq)]
+    #[derive(Debug, Copy, Clone, PartialEq, Eq, Serialize, Deserialize)]
     pub struct WallDimensions {
         pub rows: u64,
         pub cols: u64,
@@ -115,7 +146,7 @@ pub mod v2 {
     #[derive(Serialize, Deserialize, Debug, PartialEq, Eq, PartialOrd, Ord, Clone, Copy, Hash, derive_more::FromStr, derive_more::Display)]
     pub struct ProblemUid(pub uuid::Uuid);
 
-    #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Display)]
+    #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Display, Copy)]
     pub enum Method {
         #[display("Feet follow hands")]
         FeetFollowHands,
diff --git a/crates/ascend/src/models/semantics.rs b/crates/ascend/src/models/semantics.rs
index f9288fa..da42f99 100644
--- a/crates/ascend/src/models/semantics.rs
+++ b/crates/ascend/src/models/semantics.rs
@@ -3,6 +3,89 @@ use chrono::DateTime;
 use chrono::Utc;
 use std::collections::BTreeMap;
 
+impl Problem {
+    pub fn normalize(&self) -> Self {
+        let Self {
+            holds,
+            method,
+            transformation,
+        } = self;
+
+        let min_col = holds.0.iter().map(|(hold_position, _)| hold_position.col).min().unwrap_or(0);
+
+        let holds = {
+            let holds = holds
+                .0
+                .iter()
+                .map(|(hold_position, hold_role)| {
+                    let hold_position = HoldPosition {
+                        row: hold_position.row,
+                        col: hold_position.col - min_col,
+                    };
+                    (hold_position, *hold_role)
+                })
+                .collect();
+            ProblemHolds(holds)
+        };
+
+        let transformation = {
+            let mut transformation = *transformation;
+            transformation.horizontal_shift += min_col;
+            transformation
+        };
+
+        Self {
+            holds,
+            method: *method,
+            transformation,
+        }
+    }
+
+    pub fn mirror(&self) -> Self {
+        let Self {
+            holds,
+            method,
+            transformation,
+        } = self;
+
+        let min_col = holds.0.iter().map(|(hold_position, _)| hold_position.col).min().unwrap_or(0);
+        let max_col = holds.0.iter().map(|(hold_position, _)| hold_position.col).max().unwrap_or(0);
+
+        let holds = {
+            let holds = holds
+                .0
+                .iter()
+                .map(|(hold_position, hold_role)| {
+                    let HoldPosition { row, col } = *hold_position;
+                    let mut mirrored_col = col;
+                    mirrored_col += 2 * (max_col - col);
+                    mirrored_col -= max_col - min_col;
+                    let hold_position = HoldPosition { row, col: mirrored_col };
+                    (hold_position, *hold_role)
+                })
+                .collect();
+            ProblemHolds(holds)
+        };
+
+        let transformation = {
+            let mut transformation = *transformation;
+            transformation.mirror = !transformation.mirror;
+            transformation
+        };
+
+        Self {
+            holds,
+            method: *method,
+            transformation,
+        }
+        .normalize()
+    }
+
+    pub fn shift(&self, shift: i64) -> Self {
+        todo!()
+    }
+}
+
 impl UserInteraction {
     pub(crate) fn new(wall_uid: WallUid, problem_uid: ProblemUid) -> Self {
         Self {
diff --git a/crates/ascend/src/server/db.rs b/crates/ascend/src/server/db.rs
index 33ee685..a3da7c0 100644
--- a/crates/ascend/src/server/db.rs
+++ b/crates/ascend/src/server/db.rs
@@ -154,6 +154,16 @@ pub mod current {
     pub use v3::VERSION;
 }
 
+pub mod v4 {
+    use crate::models;
+    use crate::server::db::bincode::Bincode;
+    use redb::TableDefinition;
+
+    pub const VERSION: u64 = 4;
+
+    // TODO
+}
+
 pub mod v3 {
     use crate::models;
     use crate::server::db::bincode::Bincode;