diff --git a/apps/engine/src/engine/introspection.rs b/apps/engine/src/engine/introspection.rs
index 523165d..d819c96 100644
--- a/apps/engine/src/engine/introspection.rs
+++ b/apps/engine/src/engine/introspection.rs
@@ -369,7 +369,7 @@ pub(crate) fn circuit_ops(
         let snk_id = format!("snk:{sid}");
 
         if let Some(agg) = &s.aggregate {
-            let fn_label = format!("Σ {}({})", format!("{:?}", agg.func).to_uppercase(), agg.col.as_deref().unwrap_or("*"));
+            let fn_label = format!("{}({})", format!("{:?}", agg.func).to_uppercase(), agg.col.as_deref().unwrap_or("*"));
             if s.circuit.as_ref().is_some_and(|p| p.counts) {
                 // Counts-served: the fold's input is the counts pipeline's group deltas
                 // (`map_index(group) → weighted_count` in the circuit), NOT a σ over row
diff --git a/apps/pipeline-viz/README.md b/apps/pipeline-viz/README.md
index 4bf3809..0768218 100644
--- a/apps/pipeline-viz/README.md
+++ b/apps/pipeline-viz/README.md
@@ -11,7 +11,7 @@ of every node** on the canvas.
   the same ids, so nothing is reconstructed client-side — what flashes is what ran, and the
   counts you see are the engine's counters.
 - **dbsp circuit** — the exploded operator dataflow, **emitted by the engine** (`/graph`'s
-  `operators`/`opEdges`): source → Δ → σ/↦/arrange/⋈/distinct/Σ → π → sink, one box per real
+  `operators`/`opEdges`): source → Δ → σ/↦/arrange/⋈/distinct/γ → π → sink, one box per real
   execution step. Each operator carries the trace-hop id it animates under and (for the
   state-bearing operator only) the state-summary id its chips show — declared bindings, not
   client-side guesses. Dashed edges are stateful arrangements feeding joins; shared structure
@@ -26,9 +26,9 @@ In the Logical view each node card carries its dbsp identity and its live state:
 - **↦⋈ route join · STATE** — the shared equality router: an arrangement of predicate keys →
   shapes, one per family (`WHERE k = const` compiles to an index entry, not a circuit). Chips:
   live routing-index keys + routed shapes.
-- **IN-set arrange · STATE** — a shared subquery inner set (`value → contributing pks`), one per
+- **IN-set distinct · STATE** — a shared subquery inner set (`value → contributing pks`), one per
   distinct `IN (SELECT …)`. Chips: distinct values + refcount.
-- **Σ fold · STATE** — a scalar aggregation maintained as an incremental fold. Chips: the current
+- **γ fold · STATE** — a scalar aggregation maintained as an incremental fold. Chips: the current
   value (live), matching-row count, and the MIN/MAX retraction-multiset size.
 - **shape out · π** — the per-shape output stream (grouped by pk into upsert/delete envelopes).
   Chip: envelopes emitted (backfill + live).
diff --git a/apps/pipeline-viz/src/App.tsx b/apps/pipeline-viz/src/App.tsx
index dc2e777..5cc74c0 100644
--- a/apps/pipeline-viz/src/App.tsx
+++ b/apps/pipeline-viz/src/App.tsx
@@ -890,8 +890,8 @@ export default function App() {
             <span className="lg lg-table">table · Δ source</span>
             <span className="lg lg-filter">σ filter</span>
             <span className="lg lg-family">↦⋈ route join</span>
-            <span className="lg lg-sqnode">IN-set arrange</span>
-            <span className="lg lg-agg">Σ aggregate</span>
+            <span className="lg lg-sqnode">IN-set distinct</span>
+            <span className="lg lg-agg">γ aggregate</span>
             <span className="lg lg-shape">shape out</span>
             {graph?.arrangements ? (
               <span className="lg lg-serve" title="a chip on the card: the shape's data is seeded + maintained by the dbsp circuit">
@@ -905,9 +905,9 @@ export default function App() {
             <span className="lg lg-delta">Δ change</span>
             <span className="lg lg-filter">σ filter</span>
             <span className="lg lg-index">↦ key</span>
-            <span className="lg lg-sqnode">arrange (state)</span>
+            <span className="lg lg-sqnode">distinct (state)</span>
             <span className="lg lg-join">⋈ join</span>
-            <span className="lg lg-agg">Σ fold</span>
+            <span className="lg lg-agg">γ fold</span>
             <span className="lg lg-shape">π · sink</span>
             {graph?.arrangements ? <span className="lg lg-arr">dbsp index</span> : null}
             {graph?.arrangements ? <span className="lg lg-arr-counts">dbsp counts</span> : null}
diff --git a/apps/pipeline-viz/src/build-circuit.ts b/apps/pipeline-viz/src/build-circuit.ts
index 332631c..413bf49 100644
--- a/apps/pipeline-viz/src/build-circuit.ts
+++ b/apps/pipeline-viz/src/build-circuit.ts
@@ -204,7 +204,7 @@ function restrictToSelection(
 //   2. Subquery templates: subquery shapes whose maintained pipeline is structurally identical
 //      (same outer table, predicate template, projection) — differing only in their bound parameter
 //      and thus their materialized inner set — fold their inner-set chain (`sqf`/`sqp`/`dist`) into
-//      one stacked IN-SET ARRANGE and their outer chain (`sj`/`pi`/`snk`) into one stacked SINK.
+//      one stacked IN-SET DISTINCT and their outer chain (`sj`/`pi`/`snk`) into one stacked SINK.
 // Both dimensions reduce to the same mechanism: a `redirect` map (collapsed operator id → the
 // representative node that stands in for it) plus the representative nodes themselves. `collapse`
 // then drops the collapsed operators, adds the representatives, and rewrites every edge endpoint
@@ -316,7 +316,7 @@ function planGroups(g: EngineGraph): GroupPlan {
         ref,
       },
     })
-    // The inner-set chain (σ inner where → π proj → distinct) collapses to the IN-SET ARRANGE rep…
+    // The inner-set chain (σ inner where → π proj → distinct) collapses to the IN-SET DISTINCT rep…
     for (const sig of sigs) {
       redirect.set(`sqf:${sig}`, distId)
       redirect.set(`sqp:${sig}`, distId)
diff --git a/apps/pipeline-viz/src/node-meta.ts b/apps/pipeline-viz/src/node-meta.ts
index e373f8e..1a16447 100644
--- a/apps/pipeline-viz/src/node-meta.ts
+++ b/apps/pipeline-viz/src/node-meta.ts
@@ -64,7 +64,7 @@ export const KIND_META: Record<NodeKind, KindMeta> = {
   sqnode: {
     color: '#7e22ce',
     bg: '#f3e8ff',
-    tag: 'IN-SET ARRANGE · STATE',
+    tag: 'IN-SET DISTINCT · STATE',
     formula: 'distinct(π(proj) · σ(where) · inner)',
     stateful: true,
     inside:
@@ -92,7 +92,7 @@ export const KIND_META: Record<NodeKind, KindMeta> = {
   agg: {
     color: '#0d9488',
     bg: '#ccfbf1',
-    tag: 'Σ FOLD · STATE',
+    tag: 'γ FOLD · STATE',
     formula: 'fold(Σ value·w over σ(where))',
     stateful: true,
     inside:
@@ -192,7 +192,7 @@ export const KIND_META: Record<NodeKind, KindMeta> = {
   'op-fold': {
     color: '#0d9488',
     bg: '#ccfbf1',
-    tag: 'Σ FOLD · STATE',
+    tag: 'γ FOLD · STATE',
     formula: 'fold(Σ value·w)',
     stateful: true,
     inside:
@@ -256,7 +256,7 @@ export const KIND_META: Record<NodeKind, KindMeta> = {
   'arr-counts': {
     color: '#6d28d9',
     bg: '#ede9fe',
-    tag: 'DBSP COUNTS · Σ STATE',
+    tag: 'DBSP COUNTS · γ STATE',
     formula: 'map_index(group) · weighted_count',
     stateful: true,
     inside:
diff --git a/apps/pipeline-viz/src/styles.css b/apps/pipeline-viz/src/styles.css
index 7b2297b..f59affe 100644
--- a/apps/pipeline-viz/src/styles.css
+++ b/apps/pipeline-viz/src/styles.css
@@ -690,7 +690,7 @@ body,
     box-shadow: 0 0 0 0 rgba(16, 185, 129, 0);
   }
 }
-/* Aggregation detail: the prominent live scalar stat (teal, matching the Σ node). */
+/* Aggregation detail: the prominent live scalar stat (teal, matching the γ node). */
 .dp-agg {
   margin: 2px 0 10px;
   padding: 8px 12px 9px;