diff --git a/.gitmodules b/.gitmodules
index f48acab..708bae2 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,6 +1,3 @@
-[submodule "third_party/abseil-cpp"]
-	path = third_party/abseil-cpp
-	url = https://github.com/abseil/abseil-cpp.git
 [submodule "third_party/benchmark"]
 	path = third_party/benchmark
 	url = https://github.com/google/benchmark.git
diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index b9664fb..0808758 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -1,67 +1,69 @@
 cmake_minimum_required(VERSION 3.12)
-project(core VERSION 0.2.1 LANGUAGES CXX)
+project(core VERSION 0.0.1 LANGUAGES CXX)
 
 set(CMAKE_CXX_STANDARD 23)
 
 set(KLOTSKI_CORE_SRC
-        all_cases/internal/basic_ranges.cc
-        all_cases/internal/all_cases.cc
+    ranges/internal/spawn.cc
+    ranges/internal/ranges.cc
+    ranges/internal/derive.cc
 
-        common_code/internal/common_code.cc
-        common_code/internal/serialize.cc
-        common_code/internal/mirror.cc
+    all_cases/internal/basic_ranges.cc
+    all_cases/internal/all_cases.cc
 
-        raw_code/internal/raw_code.cc
-        raw_code/internal/convert.cc
-        raw_code/internal/mirror.cc
+    common_code/internal/common_code.cc
+    common_code/internal/serialize.cc
+    common_code/internal/mirror.cc
 
-        short_code/internal/convert.cc
-        short_code/internal/serialize.cc
+    raw_code/internal/raw_code.cc
+    raw_code/internal/convert.cc
+    raw_code/internal/mirror.cc
 
-        mover/internal/mover.cc
+    short_code/internal/convert.cc
+    short_code/internal/serialize.cc
 
-        fast_cal/internal/fast_cal.cc
+    mover/internal/mover.cc
 
-        group/internal/group_union.cc
-        group/internal/group.cc
-        group/internal/group_cases.cc
+    group/internal/group_union.cc
+    group/internal/group.cc
+    group/internal/group_cases.cc
 
-        ranges/internal/spawn.cc
-        ranges/internal/ranges.cc
-        ranges/internal/derive.cc
+    fast_cal/internal/fast_cal.cc
 )
 
 add_library(klotski_core STATIC ${KLOTSKI_CORE_SRC})
 target_compile_options(klotski_core PRIVATE -fno-rtti -fno-exceptions)  # option for `-fvisibility=hidden`
 target_include_directories(klotski_core PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
-target_link_libraries(klotski_core PRIVATE absl::flat_hash_map)
-target_link_libraries(klotski_core PUBLIC phmap)
+target_link_libraries(klotski_core PUBLIC phmap::phmap)
 add_library(klotski::core ALIAS klotski_core)
 
 # TODO: just for dev testing
 add_executable(klotski_core_bin main.cc)
 target_link_libraries(klotski_core_bin PRIVATE klotski_core)
 
-add_executable(codec_benchmark benchmark/codec.cc)
-target_compile_options(codec_benchmark PRIVATE -fno-rtti -fno-exceptions -fno-access-control)
-target_link_libraries(codec_benchmark PRIVATE klotski::core benchmark::benchmark_main)
+set(KLSK_BENCHMARK_OPTS -fno-rtti -fno-exceptions -fno-access-control)
+set(KLSK_BENCHMARK_LIBS klotski::core benchmark::benchmark_main bs::thread_pool)
 
-add_executable(group_benchmark benchmark/group.cc)
-target_compile_options(group_benchmark PRIVATE -fno-rtti -fno-exceptions -fno-access-control)
-target_link_libraries(group_benchmark PRIVATE klotski::core benchmark::benchmark_main)
+add_executable(bm_klsk_codec benchmark/codec.cc)
+target_compile_options(bm_klsk_codec PRIVATE ${KLSK_BENCHMARK_OPTS})
+target_link_libraries(bm_klsk_codec PRIVATE ${KLSK_BENCHMARK_LIBS})
 
-add_executable(bm_all_cases benchmark/all_cases.cc)
-target_compile_options(bm_all_cases PRIVATE -fno-rtti -fno-exceptions -fno-access-control)
-target_link_libraries(bm_all_cases PRIVATE klotski::core benchmark::benchmark_main bs::thread_pool)
+add_executable(bm_klsk_group benchmark/group.cc)
+target_compile_options(bm_klsk_group PRIVATE ${KLSK_BENCHMARK_OPTS})
+target_link_libraries(bm_klsk_group PRIVATE ${KLSK_BENCHMARK_LIBS})
 
-add_executable(bm_ranges benchmark/ranges.cc)
-target_compile_options(bm_ranges PRIVATE -fno-rtti -fno-exceptions)
-target_link_libraries(bm_ranges PRIVATE klotski::core benchmark::benchmark_main)
+add_executable(bm_klsk_all_cases benchmark/all_cases.cc)
+target_compile_options(bm_klsk_all_cases PRIVATE ${KLSK_BENCHMARK_OPTS})
+target_link_libraries(bm_klsk_all_cases PRIVATE ${KLSK_BENCHMARK_LIBS})
 
-add_executable(bm_utility benchmark/utility.cc)
-target_compile_options(bm_utility PRIVATE -fno-rtti -fno-exceptions)
-target_link_libraries(bm_utility PRIVATE klotski::core benchmark::benchmark_main)
+add_executable(bm_klsk_ranges benchmark/ranges.cc)
+target_compile_options(bm_klsk_ranges PRIVATE ${KLSK_BENCHMARK_OPTS})
+target_link_libraries(bm_klsk_ranges PRIVATE ${KLSK_BENCHMARK_LIBS})
 
-add_executable(bm_fast_cal benchmark/fast_cal.cc)
-target_compile_options(bm_fast_cal PRIVATE -fno-rtti -fno-exceptions)
-target_link_libraries(bm_fast_cal PRIVATE klotski::core benchmark::benchmark_main)
+add_executable(bm_klsk_utility benchmark/utility.cc)
+target_compile_options(bm_klsk_utility PRIVATE ${KLSK_BENCHMARK_OPTS})
+target_link_libraries(bm_klsk_utility PRIVATE ${KLSK_BENCHMARK_LIBS})
+
+add_executable(bm_klsk_fast_cal benchmark/fast_cal.cc)
+target_compile_options(bm_klsk_fast_cal PRIVATE ${KLSK_BENCHMARK_OPTS})
+target_link_libraries(bm_klsk_fast_cal PRIVATE ${KLSK_BENCHMARK_LIBS})
diff --git a/src/core/benchmark/ranges.cc b/src/core/benchmark/ranges.cc
index 42a54f9..3c9cfc5 100644
--- a/src/core/benchmark/ranges.cc
+++ b/src/core/benchmark/ranges.cc
@@ -15,7 +15,7 @@ static void SpawnRanges(benchmark::State &state) {
         kk.reserve(7311921);
 
         // for (uint32_t type_id = 0; type_id < klotski::cases::TYPE_ID_LIMIT; ++type_id) {
-            for (auto [n, n_2x1, n_1x1] : klotski::cases::BLOCK_NUM) {
+            for (auto [n, n_2x1, n_1x1] : klotski::group::BLOCK_NUM) {
                 kk.spawn(n, n_2x1, n_1x1);
             }
         // }
diff --git a/third_party/ThirdParty.cmake b/third_party/ThirdParty.cmake
index 0aefb34..78e3af2 100644
--- a/third_party/ThirdParty.cmake
+++ b/third_party/ThirdParty.cmake
@@ -1,11 +1,8 @@
 set(KLSK_THIRD_PARTY ${KLSK_ROOT_DIR}/third_party)
 
-# abseil library
-set(ABSL_PROPAGATE_CXX_STD ON)
-add_subdirectory(${KLSK_THIRD_PARTY}/abseil-cpp EXCLUDE_FROM_ALL)
-
 # parallel hashmap
 add_subdirectory(${KLSK_THIRD_PARTY}/parallel-hashmap EXCLUDE_FROM_ALL)
+add_library(phmap::phmap ALIAS phmap)
 
 if (KLSK_ENABLE_BENCHMARK)
   # google benchmark framework
diff --git a/third_party/abseil-cpp b/third_party/abseil-cpp
deleted file mode 160000
index 2f9e432..0000000
--- a/third_party/abseil-cpp
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 2f9e432cce407ce0ae50676696666f33a77d42ac