What is the security parameter K in GHOSTDAG?

The security parameter K is a mathematical constraint in GHOSTDAG that limits the size of Anticones to maintain the network's security properties. After GHOSTDAG selects a primary parent block by Blue Work, it examines the Mergeset and classifies each block as "blue" or "red." That classification is governed by K, which caps how large an Anticone — the set of blocks concurrent with a given block — is allowed to be before the block is considered potentially conflicting. For a beginner, K is the underlying guardrail that keeps the network secure as it processes many parallel blocks simultaneously: it is the mathematical boundary between honest participation and conflict.