The article introduces a representation of a formal
context by an undirected graph called a context graph with the
formal objects being the nodes of the graph. We use as a defining
property for this graph that it contains every concept extent as a
connected subgraph. The graph is not uniquely defined by this property
- we focus on those graphs that are edge-minimal and present a result
with respect to the number of their edges. We then study how the
structure of an edge-minimal context graph can be updated to adjust to
the subsequent addition of an object to the context. This leads to an
incremental construction algorithm that does not require the explicit
computation of formal concepts.