[Right triangle ⏵ may be expanded, down triangle ⏷ to close. Button = tree pop-up. × = close pop-up.]

Terminal: run. Derivation Graphs: (left-to-right) compact / full; (top-down) full / compact.

Help: blue = parse inside. Abbr.: WS: Workspace; Initial WS: initial heads for Merge after LEX lookup.

WS n, n = 1,2,... for intermediate stages after Initial WS. Final WS: when WS items converge on a single SO.
Bracketing: {...} (Merge). {...} (FormSet). At Spellout, {...} indicates free word order. [word] indicates word is optionally present.
Head Hd_{selection/features}, e.g. p_θ = predicate head p that seeks a θ-relevant (θR) IA from the WS. p_θ is a θ-seeker (θS).
v_see:θ:pst = head v has complement see, a θR EA from the WS and TNS. v is also a θS.
INFL seeks θR from its complement (not the WS).
Complementizer C comes in different flavors wrt. Force, .e.g. declarative C, interrogative C_Q and relative clause head C_rel.
Features, e.g. TNS pres/pst or DET the/a (shorthand for a bundle of semantic features).
Note: φ-features, e.g. 1sg, appear only at Spellout. Some words do not project, turn into features, e.g. determiners.

Words: the bombings were criminal

Initial WS 1: criminal_θ v_pred:_pst INFL_v:_pl bombings_the

WS 1: {criminal_θ, bombings_the} v_pred:_pst INFL_v:_pl

WS 2: {v_pred:_pst, {criminal_θ, bombings_the}} INFL_v:_pl

WS 3: {INFL_v:_pl, {v_pred:_pst, {criminal_θ, bombings_the}}}

Final WS: {C, {INFL_v:_pl, {v_pred:_pst, {criminal_θ, bombings_the}}}}

INT/EXT: {C, {INFL_v:_pl, {v_pred:_pst, {criminal_θ, bombings_the}}}}

EXT: the bombings 3pl pst be criminal

Spellout: the bombings were criminal

Parse found: the bombings 3pl pst be criminal

EXT: there 3pl pst be criminal the bombings

Spellout: there were criminal the bombings

Blocked: inconsistent with input!

Final WS: {C_Q:_{aux(pl,pst,be)}, {INFL_v:_pl, {v_pred:_pst, {criminal_θ, bombings_the}}}}

INT/EXT: {C_Q:_{aux(pl,pst,be)}, {INFL_v:_pl, {v_pred:_pst, {criminal_θ, bombings_the}}}}

EXT: pl pst be →→ the bombings 3pl pst be criminal

Spellout: 3pl pst be the bombings criminal

Spellout: were the bombings criminal

Blocked: inconsistent with input!

EXT: pl pst be →→ there 3pl pst be criminal the bombings

Spellout: 3pl pst be there criminal the bombings

Spellout: were there criminal the bombings

Blocked: inconsistent with input!