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theorem

add_balanced

proved
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module
IndisputableMonolith.RRF.Foundation.Ledger
domain
RRF
line
59 · github
papers citing
none yet

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IndisputableMonolith.RRF.Foundation.Ledger on GitHub at line 59.

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formal source

  56    omega
  57}
  58
  59theorem add_balanced (t₁ t₂ : Transaction) :
  60    (add t₁ t₂).debit + (add t₁ t₂).credit = 0 := (add t₁ t₂).balanced
  61
  62end Transaction
  63
  64/-! ## Full Ledger -/
  65
  66/-- A ledger: a sequence of transactions that globally balance. -/
  67structure Ledger where
  68  /-- The transactions in the ledger. -/
  69  transactions : List Transaction
  70  /-- Total debit. -/
  71  total_debit : ℤ := (transactions.map (·.debit)).sum
  72  /-- Total credit. -/
  73  total_credit : ℤ := (transactions.map (·.credit)).sum
  74  /-- Global balance: total debit + total credit = 0. -/
  75  global_balance : total_debit + total_credit = 0
  76
  77namespace Ledger
  78
  79/-- The empty ledger. -/
  80def empty : Ledger := {
  81  transactions := [],
  82  total_debit := 0,
  83  total_credit := 0,
  84  global_balance := by omega
  85}
  86
  87/-- A singleton ledger. -/
  88def singleton (t : Transaction) : Ledger := {
  89  transactions := [t],