Add a precondition to acceptedByCC to accept on those actions committee cannot vote

Author: carlostome

src/Ledger/Conway/Specification/Ratify.lagda.md

@@ -284,8 +284,11 @@ utilizes the following auxiliary definitions.
 
     +  all commitee members vote `no`{.AgdaInductiveConstructor}.
 
-+  `mT`{.AgdaFunction}: This is the threshold of the `CC`{.AgdaInductiveConstructor}.
-   It may be `nothing`{.AgdaInductiveConstructor}.
++  `mT`{.AgdaFunction}: This is the threshold of the
+   `CC`{.AgdaInductiveConstructor}.  In case it is
+   `nothing`{.AgdaInductiveConstructor}, the `CC`{.AgdaInductiveConstructor} is
+   not allowed to vote and the action is accepted automatically (e.g., for
+   `NoConfidence` or `UpdateCommittee` actions).
 
 +  `stakeDistr`{.AgdaFunction} computes the stake distribution.  Note that every
    constitutional committe member has a stake of 1, giving them equal voting power.
@@ -363,8 +366,7 @@ module AcceptedByCC (currentEpoch : Epoch)
   acceptedStake  = ∑[ x ← stakeDistr ∣ actualVotes ⁻¹ Vote.yes ] x
   totalStake     = ∑[ x ← stakeDistr ∣ dom (actualVotes ∣^ (❴ Vote.yes ❵ ∪ ❴ Vote.no ❵)) ] x
 
-  accepted = (acceptedStake /₀ totalStake) ≥ t
-    × (sizeActiveCC ≥ ccMinSize ⊎ (Is-nothing mT × ccMinSize ≡ 0))
+  accepted = Is-just mT → (sizeActiveCC ≥ ccMinSize) × (acceptedStake /₀ totalStake) ≥ t
 ```
 
 ```agda
@@ -667,8 +669,12 @@ opaque
   Is-nothing? {x = x} = All.dec (const $ no id) x
     where import Data.Maybe.Relation.Unary.All as All
 
+  Is-just? : ∀ {A : Set} {x : Maybe A} → Dec (Is-just x)
+  Is-just? {x = x} = Any.dec (const $ yes tt) x
+    where import Data.Maybe.Relation.Unary.Any as Any
+
   acceptedByCC? : ∀ Γ es st → Dec (acceptedByCC Γ es st)
-  acceptedByCC? _ _ _ = _ ℚ.≤? _ ×-dec (_ ≥? _ ⊎-dec (Is-nothing? ×-dec ¿ _ ¿))
+  acceptedByCC? _ _ _ = Is-just? →-dec (_ ≥? _ ×-dec _ ℚ.≤? _ )
 
   acceptedByDRep? : ∀ Γ es st → Dec (acceptedByDRep Γ es st)
   acceptedByDRep? _ _ _ = _ ℚ.≤? _