From c2ff09441d4cfdac5b9bccb28291c9bc304af921 Mon Sep 17 00:00:00 2001
From: Paul Hauner <paul@paulhauner.com>
Date: Tue, 1 Mar 2022 18:34:53 +1100
Subject: [PATCH 1/3] Allow any non-merge block

---
 sync/optimistic.md | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/sync/optimistic.md b/sync/optimistic.md
index 8e6acc442..4f6637cbc 100644
--- a/sync/optimistic.md
+++ b/sync/optimistic.md
@@ -81,10 +81,17 @@ def is_execution_block(block: BeaconBlock) -> bool:
 
 ```python
 def is_optimistic_candidate_block(opt_store: OptimisticStore, current_slot: Slot, block: BeaconBlock) -> bool:
+	if is_execution_block(opt_store.blocks[block.parent_root]):
+		return True
+
     justified_root = opt_store.block_states[opt_store.head_block_root].current_justified_checkpoint.root
-    justified_is_execution_block = is_execution_block(opt_store.blocks[justified_root])
-    block_is_deep = block.slot + SAFE_SLOTS_TO_IMPORT_OPTIMISTICALLY <= current_slot
-    return justified_is_execution_block or block_is_deep
+    if is_execution_block(opt_store.blocks[justified_root]):
+		return True
+
+	if block.slot + SAFE_SLOTS_TO_IMPORT_OPTIMISTICALLY <= current_slot:
+		return True
+
+	return False
 ```
 
 Let only a node which returns `is_optimistic(opt_store, head) is True` be an *optimistic
@@ -99,14 +106,21 @@ behaviours without regard for optimistic sync.
 ### When to optimistically import blocks
 
 A block MAY be optimistically imported when
-`is_optimistic_candidate_block(opt_store, current_slot, block)` returns
-`True`. This ensures that blocks are only optimistically imported if either:
+`is_optimistic_candidate_block(opt_store, current_slot, block)` returns `True`.
+This ensures that blocks are only optimistically imported if one or more of the
+following are true:
 
+1. The parent of the block has execution enabled.
 1. The justified checkpoint has execution enabled.
 1. The current slot (as per the system clock) is at least
    `SAFE_SLOTS_TO_IMPORT_OPTIMISTICALLY` ahead of the slot of the block being
    imported.
 
+In effect, there are restrictions on when a *merge block* can be optimistically
+imported. The merge block is the first block in any chain where
+`is_execution_block(block) == True`. Any descendant of a transition block may
+be imported optimistically at any time.
+
 *See [Fork Choice Poisoning](#fork-choice-poisoning) for the motivations behind
 these conditions.*
 

From f071931e46f30de86721fe18298746d7d814bd52 Mon Sep 17 00:00:00 2001
From: Paul Hauner <paul@paulhauner.com>
Date: Tue, 1 Mar 2022 18:46:39 +1100
Subject: [PATCH 2/3] Address indenting

---
 sync/optimistic.md | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/sync/optimistic.md b/sync/optimistic.md
index 4f6637cbc..8b3c1a730 100644
--- a/sync/optimistic.md
+++ b/sync/optimistic.md
@@ -81,17 +81,17 @@ def is_execution_block(block: BeaconBlock) -> bool:
 
 ```python
 def is_optimistic_candidate_block(opt_store: OptimisticStore, current_slot: Slot, block: BeaconBlock) -> bool:
-	if is_execution_block(opt_store.blocks[block.parent_root]):
-		return True
+    if is_execution_block(opt_store.blocks[block.parent_root]):
+        return True
 
     justified_root = opt_store.block_states[opt_store.head_block_root].current_justified_checkpoint.root
     if is_execution_block(opt_store.blocks[justified_root]):
-		return True
+        return True
 
-	if block.slot + SAFE_SLOTS_TO_IMPORT_OPTIMISTICALLY <= current_slot:
-		return True
+    if block.slot + SAFE_SLOTS_TO_IMPORT_OPTIMISTICALLY <= current_slot:
+        return True
 
-	return False
+    return False
 ```
 
 Let only a node which returns `is_optimistic(opt_store, head) is True` be an *optimistic

From bf25d323fc77535f7a168452756257b92b78a54e Mon Sep 17 00:00:00 2001
From: Paul Hauner <paul@paulhauner.com>
Date: Wed, 2 Mar 2022 19:03:06 +1100
Subject: [PATCH 3/3] Use merge consistently

---
 sync/optimistic.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sync/optimistic.md b/sync/optimistic.md
index 8b3c1a730..3237c3f65 100644
--- a/sync/optimistic.md
+++ b/sync/optimistic.md
@@ -118,8 +118,8 @@ following are true:
 
 In effect, there are restrictions on when a *merge block* can be optimistically
 imported. The merge block is the first block in any chain where
-`is_execution_block(block) == True`. Any descendant of a transition block may
-be imported optimistically at any time.
+`is_execution_block(block) == True`. Any descendant of a merge block may be
+imported optimistically at any time.
 
 *See [Fork Choice Poisoning](#fork-choice-poisoning) for the motivations behind
 these conditions.*