diff --git a/README.md b/README.md
index 3de37487..85529bfb 100644
--- a/README.md
+++ b/README.md
@@ -119,7 +119,7 @@ This readme file is used mostly to document project dependencies
 ## Local build (Windows 10+)
 
 - this is main developers build
-- Install Python 3.9, NodeJS, VSCode, Docker Desktop
+- Install Python 3.12, NodeJS, VSCode, Docker Desktop
 - copy import wheels from ConceptCore to rsconcept/backend/import
 - run rsconcept/backend/LocalEnvSetup.ps1
 - use VSCode configs in root folder to start development
@@ -140,6 +140,7 @@ This readme file is used mostly to document project dependencies
 
 ## Production build
 
+- provide proper pyconcept wheel (ConceptCore) at 'rsconcept/backend/import/\*.whl'
 - provide secrets: 'secrets/db_password.txt', 'django_key.txt', 'email_host.txt', 'email_password.txt', 'email_user.txt'
 - check if you need to change SSL/TLS and PORT in 'rsconcept\backend\.env.prod'
 - setup domain names for application and API in configs: 'frontend\env\.env.production', 'rsconcept\backend\.env.dev', 'nginx\production.conf'
diff --git a/rsconcept/backend/Dockerfile b/rsconcept/backend/Dockerfile
index db53d958..0493d10b 100644
--- a/rsconcept/backend/Dockerfile
+++ b/rsconcept/backend/Dockerfile
@@ -3,16 +3,26 @@
 # ==========================================
 FROM ubuntu:jammy as python-base
 
-RUN apt-get update -qq && \
-    apt-get upgrade -y && \
-    apt-get install -y --no-install-recommends \
-        python3 \
-        python3-pip \ 
-        python-is-python3 && \
-    rm -rf /var/lib/apt/lists/*
+ENV DEBIAN_FRONTEND=noninteractive
 
-RUN pip install --upgrade pip && \
-    pip install wheel
+RUN apt-get update -qq && \
+    apt-get full-upgrade -y && \
+    apt-get install -y --no-install-recommends \
+        curl \
+        gpg-agent \
+        software-properties-common && \
+    add-apt-repository -y ppa:deadsnakes/ppa && \
+    add-apt-repository -y ppa:ubuntu-toolchain-r/test && \
+    apt-get install -y --no-install-recommends \
+        python3.12 \
+        libstdc++6 && \
+    curl -sS https://bootstrap.pypa.io/get-pip.py | python3.12 && \
+    python3.12 -m pip install --upgrade pip && \
+    python3.12 -m pip install wheel && \
+    apt-get autoclean -y && \
+    apt-get autoremove -y && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/*
 
 # ========= Builder ==============
 FROM python-base as builder
@@ -23,7 +33,7 @@ ENV PYTHONUNBUFFERED 1
 
 COPY ./requirements.txt ./
 COPY ./import/*linux*.whl ./wheels/
-RUN pip wheel \
+RUN python3.12 -m pip wheel \
         --no-cache-dir --no-deps \
         --wheel-dir=/wheels -r requirements.txt
 
diff --git a/rsconcept/backend/apps/rsform/tests/s_views/t_operations.py b/rsconcept/backend/apps/rsform/tests/s_views/t_operations.py
index 51407ec0..3bd8facd 100644
--- a/rsconcept/backend/apps/rsform/tests/s_views/t_operations.py
+++ b/rsconcept/backend/apps/rsform/tests/s_views/t_operations.py
@@ -49,11 +49,11 @@ class TestInlineSynthesis(EndpointTester):
         ks1_x1 = self.schema1.insert_new('X1', term_raw='KS1X1') # -> delete
         ks1_x2 = self.schema1.insert_new('X2', term_raw='KS1X2') # -> X2
         ks1_s1 = self.schema1.insert_new('S1', definition_formal='X2', term_raw='KS1S1') # -> S1
-        ks1_d1 = self.schema1.insert_new('D1', definition_formal='S1\X1\X2') # -> D1
+        ks1_d1 = self.schema1.insert_new('D1', definition_formal=r'S1\X1\X2') # -> D1
         ks2_x1 = self.schema2.insert_new('X1', term_raw='KS2X1') # -> delete
         ks2_x2 = self.schema2.insert_new('X2', term_raw='KS2X2') # -> X4
         ks2_s1 = self.schema2.insert_new('S1', definition_formal='X2×X2', term_raw='KS2S1') # -> S2
-        ks2_d1 = self.schema2.insert_new('D1', definition_formal='S1\X1\X2') # -> D2
+        ks2_d1 = self.schema2.insert_new('D1', definition_formal=r'S1\X1\X2') # -> D2
         ks2_a1 = self.schema2.insert_new('A1', definition_formal='1=1') # -> not included in items
 
         data = {
@@ -83,5 +83,5 @@ class TestInlineSynthesis(EndpointTester):
         self.assertEqual(result['S2']['term_raw'], ks2_s1.term_raw)
         self.assertEqual(result['S1']['definition_formal'], 'X2')
         self.assertEqual(result['S2']['definition_formal'], 'X4×X4')
-        self.assertEqual(result['D1']['definition_formal'], 'S1\S2\X2')
-        self.assertEqual(result['D2']['definition_formal'], 'S2\S1\X4')
+        self.assertEqual(result['D1']['definition_formal'], r'S1\S2\X2')
+        self.assertEqual(result['D2']['definition_formal'], r'S2\S1\X4')
diff --git a/rsconcept/backend/apps/rsform/tests/s_views/t_rsforms.py b/rsconcept/backend/apps/rsform/tests/s_views/t_rsforms.py
index 2e8b2c23..0c5ec99b 100644
--- a/rsconcept/backend/apps/rsform/tests/s_views/t_rsforms.py
+++ b/rsconcept/backend/apps/rsform/tests/s_views/t_rsforms.py
@@ -307,7 +307,7 @@ class TestRSFormViewset(EndpointTester):
         d2 = self.schema.insert_new('D2')
         d3 = self.schema.insert_new(
             alias='D3',
-            definition_formal='X1 \ X2'
+            definition_formal=r'X1 \ X2'
         )
         
         data = {'substitutions': []}
@@ -343,7 +343,7 @@ class TestRSFormViewset(EndpointTester):
         self.assertEqual(response.status_code, status.HTTP_200_OK)
 
         d3.refresh_from_db()
-        self.assertEqual(d3.definition_formal, 'D1 \ D2')
+        self.assertEqual(d3.definition_formal, r'D1 \ D2')
 
 
     @decl_endpoint('/api/rsforms/{item}/cst-create', method='post')
diff --git a/rsconcept/backend/cctext/resolver.py b/rsconcept/backend/cctext/resolver.py
index 7e4a5f8e..e9df3df7 100644
--- a/rsconcept/backend/cctext/resolver.py
+++ b/rsconcept/backend/cctext/resolver.py
@@ -9,8 +9,10 @@ from .conceptapi import inflect_dependant
 from .context import TermContext
 from .reference import EntityReference, SyntacticReference, parse_reference, Reference
 
+
 _REF_ENTITY_PATTERN = re.compile(r'@{([^0-9\-][^\}\|\{]*?)\|([^\}\|\{]*?)}')
 
+
 def extract_entities(text: str) -> list[str]:
     ''' Extract list of entities that are referenced. '''
     result: list[str] = []
@@ -67,6 +69,9 @@ class Position:
     start: int = 0
     finish: int = 0
 
+    def __hash__(self) -> int:
+        return hash((self.start, self.finish))
+
 
 @dataclass
 class ResolvedReference:
@@ -76,6 +81,9 @@ class ResolvedReference:
     pos_input: Position = Position()
     pos_output: Position = Position()
 
+    def __hash__(self) -> int:
+        return hash((self.resolved, self.pos_input, self.pos_output, self.ref.to_text()))
+
 
 class Resolver:
     ''' Text reference resolver '''
diff --git a/rsconcept/backend/entrypoint.sh b/rsconcept/backend/entrypoint.sh
index dff4dec6..e1a33d1f 100644
--- a/rsconcept/backend/entrypoint.sh
+++ b/rsconcept/backend/entrypoint.sh
@@ -12,8 +12,8 @@ then
 fi
 
 cd $APP_HOME
-python $APP_HOME/manage.py collectstatic --noinput --clear
-python $APP_HOME/manage.py migrate
+python3.12 $APP_HOME/manage.py collectstatic --noinput --clear
+python3.12 $APP_HOME/manage.py migrate
 
 # Execute given input command
 exec "$@"
\ No newline at end of file
diff --git a/rsconcept/backend/requirements.txt b/rsconcept/backend/requirements.txt
index 1def7e31..2231408a 100644
--- a/rsconcept/backend/requirements.txt
+++ b/rsconcept/backend/requirements.txt
@@ -1,8 +1,8 @@
 tzdata==2024.1
-Django==4.2.11
+Django==5.0.3
 djangorestframework==3.15.1
 django-cors-headers==4.3.1
-django-filter==24.1
+django-filter==24.2
 drf-spectacular==0.27.1
 coreapi==2.3.3
 pymorphy3==2.0.1