Graph
Purchase price history: what price, when, under which contract
A usable purchase price history keeps more than the latest known rate: it keeps every price actually invoiced, with its date, its entity, its site and the contract that governed it at the time. Graph does not overwrite facts, it timestamps them. The March price is still readable in September.
The problem
The list price is not what you paid
The price printed in the rate schedule is a reference price. The one that was invoiced depends on a volume rebate reached in the third quarter, an amendment signed in April, an indexation clause applied late, a surcharge that appeared on one entity only. The gap between the two shows up only by reopening the invoices, and nobody reopens twelve months of invoices before a negotiation.
Most systems are no help: the item record carries the current price, and the update erases the previous one. You know what you pay today, rarely what you paid eighteen months ago, and almost never under which contract. Price memory stays individual, held by the buyer who ran the last negotiation.
Every invoice creates knowledge. Without a graph, it goes straight back into a PDF.
Facts timestamped, never replaced
This is the fifth step in building the graph, and the one that makes history possible. Every new document updates the graph; it does not rewrite the previous state, it adds a dated fact alongside it.
- Every price enters the graph with its period of validity, its supplier, its reference, its unit of measure and the entity that paid it.
- The contract, amendment or schedule of unit prices that governed that price on that date stays attached to the relationship: you read the price and its rule together.
- An increase does not replace the previous value: it opens a new period. Both coexist, and the curve rebuilds itself with no manual work.
- Every point on the curve opens onto the invoice line it came from: document, page, line, date. A price with no source never enters the graph.
- Units and currencies are brought back to a common base, with the conversion factor and the rate used, otherwise two consecutive prices do not compare.
The history is therefore not a frozen export recomputed each quarter: it is the natural state of the graph, filling up while the agents handle your paperwork. Nothing has to be rebuilt, because nothing was overwritten.
What a dated history makes computable
- The same price by entity, by site and by period
- What price do we pay for the same reference depending on the entity, the site and the period, and which contract governs each of those prices? The question crosses supplier, item, contract and time: only dated, connected facts answer it.
- The indexation clauses coming due
- Which indexation clauses fall due within 90 days, and on which volumes already committed? The clause comes from the contract, the volumes from orders and invoices: bringing them together assumes all three are linked and dated.
- Preparing a renegotiation
- A renegotiation then starts from what was actually invoiced, not from the theoretical rate shown in the schedule. You arrive with the prices paid, their dates, their entities and the clause that applied to each one.
Each of those answers stays verifiable line by line. That is the condition for a figure to hold up in front of a supplier: it is worth something only if it opens onto the document that carries it. Every extracted value stays linked to the exact place in the document where it was read.
Memory stops being individual. A renegotiation starts from what was actually invoiced, not from the theoretical rate.
Procurement intelligence · Graph
All your purchasing knowledge, connected and queryable.
Turns the documents the agents have already read (contracts, amendments, schedules of unit prices, rate cards, purchase orders, goods receipts, invoices, credit notes) into a typed graph built on a procurement ontology that ships with the product: entities joined by explicit relationships, each one tied to the document, the page and the line it came from. An edge without a source never enters the graph.
Memory stops being individual. A renegotiation starts from what was actually invoiced, not from the theoretical rate.
What Graph detects
- The same supplier under several legal entities
- The same item under several references depending on the supplier
- Units of measure that do not compare
- An internal classification that has drifted
- Contracts nobody can tell still cover the spend in progress
- Credit notes promised and never applied to the invoice they came from
Nothing is lost. Everything can be checked, everything can be proven.
- The contract clause and the invoice line, highlighted side by side.
- Every extracted value stays linked to the exact place in the document where it was read.
- The same case produces the same decision, today as in six months: the rules are applied deterministically.
- No discrepancy is set aside in silence. Anything that matches no rule is raised, with its reason.
- The agent records what it did, in the order it did it: who, what, how much, when.
Frequently asked questions
How does the graph keep the purchase price history?
Every new document adds dated facts instead of replacing the earlier ones. A price enters with its period of validity, its supplier, its reference, its unit and the entity that paid it. An increase opens a new period without erasing the old one, which keeps the curve queryable over time.
Can we tell which contract applied on a given date?
Yes. The relationship that carries the price also carries the contract, amendment or rate schedule in force on that date, along with the document line it came from. You read the price, its period and its rule together, without reopening the contract file.
How do I check a Zylio conclusion?
Every discrepancy opens onto its evidence: the contract clause and the invoice line, highlighted side by side, with the calculation shown.
Does Zylio replace my ERP?
No. Your ERP runs the process and remains the source of truth. Zylio handles the exception, on top of it, and feeds the results back. No additional development inside your system.
Measurable impact in every environment
More than 5 million procurement documents analysed
Between 1 and 7% of margin recovered
on the scope analysed
From 15 to 45% of time given back to teams, per FTE
depending on the scope and on data maturity
Zylio fits into your existing ecosystem.
The ERP runs the process. Zylio handles the exception and recovers the value that escapes it: invoices without a purchase order, line-by-line price discrepancies, duplicates and overbilling, off-contract spend.
Your data under high security.
Zylio meets the most demanding standards, and nothing is committed without your approval.
- Certifications
- Hosting
- Encryption
- Access
Read next
- Graph: the knowledge graph of your procurementThe parent page: how the graph is built, queried and verified.
- The procurement ontology: the blueprint before the houseThe blueprint a relationship must conform to before it can be written.
- Unified supplier master dataThe same supplier, only once: company names grouped, duplicates detected, references aligned.
- Procurement data traceabilityEvery point on the curve opens onto the invoice line it came from.
- Graph or data warehouseWhy a question crossing time and entities changes in nature.
See what this looks like on your own data
Twenty minutes, on a spend category of your choosing. We show you what the agents detect, with the evidence behind it.
- No commitment, on your own data
- Result in 3 weeks
- 20 minutes, no sales pitch
- Your data stays hosted in France
- No change of tool or process